Stokastic Sims Settings: How To Tune Exposure And ROI Boosts For MLB DFS

Most of the questions I get about the Stokastic Sims settings are not "which players are good." They're the ones a subscriber asked in our sim-tools support channel: how much should I actually move stack exposure, player exposure, and the ROI boosts, and when is leaving the defaults alone the smarter play? That is the right instinct, because the fastest way to break a good simulation is to override it with a hunch. Below is how I set the dials for MLB DFS tournaments on DraftKings and FanDuel, what each control is really doing, and the short list of moments where deviating from the defaults improves your build instead of hurting it. If you have never run the tool end to end, start with how to use the MLB DFS Sims for the full workflow, then come back here to tune it. Pull up a live board in the MLB DataHub to follow along.

TL;DR: How To Set Your Stokastic Sims

If you only take four things from this guide, take these:

• Respect The Defaults. The Stokastic Sims solve a win-equity problem across tens of thousands of simulated contests; the tool surfaces the lineups with the best simulated ROI, so every override is you betting you know something it does not.
• Field Ownership And Your Exposure Are Different Dials. Fix the projected field first (e.g. bump a chalk ace the tool has at 22% when he is really a 35% play), because leverage is measured against it, then shape your own pool.
• Stack Exposure Is The Highest-Leverage MLB Setting. Only push a team's stack above default for a correlated reason: wind out, a top home-run park, or a fly-ball starter. Never "I like this team."
• Boost The Exception, Not The Rule. Two or three players a slate, in small nudges, after lineups post, then re-favorite (boosts and caps are end-of-process tweaks; only pool size and ownership force a re-run). If you cannot name the edge, set it back to zero.

The rest of this guide is how far to move each dial, with a worked MLB example at the end.

What The Sims Are Doing Before You Touch A Setting

The mental model that makes every setting decision easier is this. The Stokastic Sims (the Contest Sims) build a large pool of lineups, drop that pool into a modeled tournament field built from projected ownership, and play the slate out tens of thousands of times. Every lineup comes back with a simulated ROI rank, which is its expected return across all of those imagined nights against the contest payout structure, not its projected score. That distinction is the whole point: you are optimizing for win probability across thousands of outcomes, not for one best-guess total.

One scope note before the dials: the simulated ROI and the leverage math below are tournament (GPP) tools. For cash games (double-ups and 50/50s) you are only trying to beat about half the field, so you sort your pool by raw projection and take the highest-floor build instead of chasing simulated ROI. Everything that follows assumes you are building for GPPs.

Used a generic DFS optimizer before? The exposure and boost controls will feel familiar, but they are doing something more specific here. In a single-point optimizer, an exposure cap just limits how often a name appears. In the Sims, your exposures and boosts change the pool that gets simulated, so a small nudge ripples through thousands of contests. That is exactly why the defaults are worth respecting: they are already tuned to the win-equity math. Your job is targeted intervention, not a full manual rebuild. For the deeper case on why simulation beats a static optimizer, see DFS sims vs optimizers.

The one rule that governs every setting below: a change to a Sims setting is you telling the model something it does not already know. If you cannot say out loud what information your adjustment adds, do not make it. Adjust on information, never on instinct.

The Settings Cheat Sheet

The whole toolbox, in one place before we go dial by dial:

Setting	What it controls	Default posture	Move it when	Forces a re-run?
Pool Size (The Simulated Field)	How realistic the contest you grade against is	Match it to the contest you're actually entering	You move up to a bigger-field contest (bigger isn't better)	Yes, a generation input
Field Ownership	How the simulated field rosters players	Trust the projected ownership	You have a real read that a player will be more or less popular than projected	Yes, it reshapes the field
Player Exposure Caps	A hard ceiling on how often a player lands in YOUR pool	Let the Sims set exposure	You need a firm lid on one player for many-entry play	No; apply it at the end
Stack Exposure	How often a team stack appears in your pool	Keep the pre-loaded stack shapes	Weather, a park, or an opposing-arm read the model underweights	No; apply it at the end
ROI / Player Boosts	A manual up or down nudge on a player	Zero, for almost everyone	A genuine edge the model lacks (late news, a leverage thesis)	No; re-favorite instead

The rest of this guide is how far to move each of these, and how to keep your changes from quietly turning the simulation back into a lineup you built by feel. Notice the split in that last column: only the two dials that change the simulated field itself, pool size and ownership, force a re-run. Everything else is a finishing tweak you apply at the end, then re-favorite.

Pool Size: Match The Simulated Field To Your Contest

The first dial to get right is pool size, and it is the one most people misread. Pool size is not how many lineups you get back; it is how big a field of simulated opponents the Sims build to model the contest you are entering. A 2,000 pool is a 2,000-entry room for your lineups to compete against; a 10,000 pool models a large-field tournament. The Sims play that field out tens of thousands of times and the tool surfaces the builds with the best simulated ROI against it.

Because pool size is the simulated field, the rule is realism, not size: match it to the contest you are actually playing. A small single-entry contest wants a small pool; a milly-maker wants a big one. A giant pool modeling a contest you never entered gives you worse lineups, not better ones, because it grades your builds against the wrong room. And since pool size is a generation input, changing it forces a full re-run (the whole field regenerates), so set it before you build, not as a last-second tweak. (The higher Data + Sims and Sims MAX tiers let you build larger pools when a big-field contest actually calls for one.)

The one-line read: pool size describes the room you walked into, so pick the field that behaves like your real contest and re-run once. Do not reach for the biggest number out of habit before you finalize.

Field Ownership Vs Your Exposure: Two Different Dials

This is the setting people mix up most, so it gets its own section. There are two separate ownership concepts in the Sims and they do opposite jobs:

• Projected Field Ownership is the tool's estimate of how the rest of the field will roster each player. Boosting it changes the simulated opponents you are trying to beat.
• Your Pool Exposure is how often your own lineups use a player.

You adjust field ownership to make the simulated field more realistic, and you adjust your exposure to shape your actual entries. Getting the field right matters because leverage is defined against it: a low-owned bat only pays off if the field really is light on him. So before you cap or boost anything in your own pool, sanity-check the projected ownership against your read. If a popular ace is going to be chalkier than the model shows, nudge the field ownership up first, regenerate, and let the simulated leverage math re-solve around the corrected field. Ownership and leverage are the engine of GPP scoring; if that idea is new, our DFS ownership and leverage guide covers it in full.

Player Exposure Caps: A Hard Ceiling, Not A Steering Wheel

The exposure cap is a hard ceiling on how often one player can appear in your pool, and that is all it is. The mistake is opening the tool and immediately hand-capping twenty players to match your gut. That throws away the win-equity solution you are paying for, and capping several players at once, especially at a multi-slot position like the two pitcher spots, can silently kill good lineup combinations the sim would otherwise have found.

How I actually use it:

• Default: let the Sims set your exposures from the simulated ROI. That is the calibrated answer.
• Cap To Stop Over-Concentration when you fire many lineups. In a large single-entry or 3-max GPP I let a top play run high, because concentrating in your best build is correct there. In a 150-max build, I set a hard cap on any single hitter (say 40%) so a bad night from one bat does not sink the whole pool.
• Want MORE Of A Player, Not Less? Don't reach for a "minimum," because there isn't one. Give him a positive ROI boost and re-favorite; his lineups get favored up and his exposure climbs while the field stays realistic.

The cap is a scalpel for one player, not a way to reshape a pool. And because it is a finishing tweak, not a generation input, you apply it at the end and simply re-favorite, with no re-run required. Move in small steps: a 40% cap and a re-favorite will teach you more than yanking one from 70% to 20% in a single move.

Set the field first, then let the Sims do the building. Get pool size and ownership right, then read the simulated-ROI board and export the top builds instead of rebuilding lineups by hand. If you want to try these controls on a live slate, the Stokastic Sims live on the Data + Sims and Sims MAX tiers and code SIMTUNE10 takes 10% off your first payment: tune your first slate.

Stack Exposure: The Highest-Leverage MLB Dial

Baseball is a stacking sport, so stack exposure is the highest-leverage setting on this list. The Sims come pre-loaded with the stack shapes MLB DFS commonly uses (like 5-3 and 5-2-1 builds on DraftKings, 4-4 and 4-3 on FanDuel), and they account for batting-order correlation for you, so your stacks are built from correlated, grouped-in-the-order bats rather than scattered one-offs. Leave those shapes alone unless you disagree with the field's construction, not just its players.

When should you push a specific team's stack exposure above what the sim wants? Only for a correlated edge the model may underweight, and MLB gives you concrete ones:

• Weather. Wind blowing out at a hitter's park is a real, namable reason to want more of that game's bats. That is information the base projections can be slow to fully price.
• Park. A middle-of-the-pack lineup in a top home-run park plays up; the same bats in a pitcher's park play down.
• The Opposing Arm. A team stacked against a fly-ball starter with home-run problems is a stack you can justify boosting.

Notice the pattern: every reason is a correlation argument, not "I like this team." Absent weather, park, or an opposing-pitcher edge, let the pre-loaded stack exposure ride, and lean on the Top Stacks Tool to see which teams the model and the field already favor before you override anything. For the full framework, our MLB DFS stacking guide pairs with this. And remember cash and GPP want opposite postures here: cash leans on a tight core of the highest-floor bats, while large-field GPPs want more distinct stacks and more leverage. If you find yourself building one lineup for both, read GPP vs cash DFS first, because that is a different setup, not a different exposure number.

ROI And Player Boosts: The Scalpel, Not The Hammer

The Boost arrows (a positive or negative nudge on an individual player) are the most powerful and most abused control in the tool. A boost overrides what the simulation concluded, so every boost is a small bet that you know something the model does not.

Used right, that is exactly when to reach for it: confirmed late news the projections have not caught, a batting-order bump, or a leverage read you are willing to stand behind. Used wrong, boosting ten players by a lot turns your simulated ROI board back into the manual lineup you would have built anyway, which defeats the entire reason to simulate.

My guardrails for boosts:

1. Boost the exception, not the rule. Most slates I touch two or three players, tops.
2. Small nudges, then re-favorite. A boost is a finishing tweak, so you don't re-run the sim; you re-favorite and pull your lineups again. See what one boost does to the board before stacking another on top.
3. Wait for confirmed lineups. The single best time to boost or fade is once a batting order posts and a name moves up, out, or into a platoon. Late swap is the highest-value in-slate action there is; if a bat gets scratched, the boost you set this morning needs revisiting.

If you cannot name the edge a boost represents, that is your signal to set it back to zero and trust the sim.

Contest-Type Presets: One Slate, Different Dials

The same board wants different settings depending on which tournament you are entering. This is how I shift the posture by GPP type (cash is a separate build, covered right below the table).

GPP Type	Exposure posture	Stacks	Boosts
Single-Entry / Small-Field GPP	Concentrated in your best simulated builds	A couple of your strongest correlated stacks	Sparingly, for a real edge
Large-Field / Many-Entry GPP	Wider, with hard caps on any one player	More distinct stacks, more leverage	Selective leverage boosts off chalk

The through-line: as the field gets bigger and the payout gets top-heavy, you widen exposure, add unique stacks, and lean into leverage. As the field shrinks, you tighten around your best simulated builds. The Sims will do most of this for you once you have the field ownership and GPP type set correctly; the presets above are the manual overlay, not a replacement for the simulation.

Cash games are the exception, not another preset. Double-ups and 50/50s only ask you to beat about half the field, so they are not a leverage-tuning exercise. The staff method is simple: build your pool as usual, but sort the output by raw projection instead of simulated ROI and take the highest-floor build. You are chasing the safest lineup, not the contrarian one. The exposure, stack, and boost dials in this guide are for GPPs. If cash versus GPP is new to you, GPP vs cash DFS covers why they need opposite builds.

A Quick Worked Example

Say it is a hitter-friendly MLB main slate and you are firing a 150-entry GPP. The projected field is piling onto the day's most expensive ace, a $10,600 arm the tool shows at 22% projected ownership. Here is the setting sequence I would run, in order:

Step	Dial	The move	Why
1	Field ownership	Bump the $10,600 ace from 22% to the ~35% he will really draw, then re-run	Ownership is a generation input; an honest field makes the whole board honest
2	Stack exposure	Let the windy park's team run a touch hot, since it is already 3rd in Top Stacks	A correlated weather + park edge the base numbers price slowly
3	Player exposure cap	Cap any single hitter at ~40% so no one bat sinks the 150-entry pool	Many-entry needs a hard ceiling on concentration
4	ROI boost	A modest positive boost on a $5,400 bat sitting at 6% projected ownership, then re-favorite	Force a real leverage read the field is light on (no re-run needed)

Notice the order: only Step 1 changes the field, so it is the only step that re-runs; Steps 2 through 4 are finishing tweaks I apply at the end and re-favorite. The row I keep coming back to is Step 4. That $5,400 hitter at 6% projected ownership is the kind of leverage piece that can separate a big-field build: if he goes off in a windy park the field barely rostered him, my boosted lineups jump the pack, and the 40% cap on the chalk elsewhere means one cold bat cannot sink the pool. Set the field, apply the tweaks, then I read the simulated-ROI board, where the tool surfaces the top builds by expected return, and export. That is the entire discipline: intervene where you have an edge, and let the Sims solve everything else.

The Bottom Line

The defaults in the Stokastic Sims are not a starting point to be overridden; they are a calibrated solution to a hard probability problem. The whole workflow reduces to one distinction: the two dials that change the simulated field, pool size and field ownership, are set up front and force a re-run, while the finishing dials, exposure caps and ROI boosts, go on at the very end, and you re-favorite instead of rebuilding. Correct the field, match your pool size to the contest, cap for many-entry play, and boost only the two or three players where you have a real edge. For cash, set the leverage aside and build around projection, floor, and confirmed lineups instead. Move the dials with a reason, in small steps, and re-favorite between finishing tweaks. Do that and the tool works with you; override it on feel and you have just built lineups by hand with extra steps.

FAQ

How much should I change the exposure settings in the Stokastic Sims? As little as possible. Let the Sims set exposures from simulated ROI by default, and reach for an exposure cap only for a specific reason: a hard ceiling to avoid over-concentration in many-entry play. To get MORE of a player, use a positive ROI boost, not a "minimum." Move in small steps and re-favorite to see the effect, since caps and boosts do not require a re-run.

What pool size should I use in the Sims? Match it to the contest you are actually entering, not the biggest option. Pool size is the simulated field, so a realistic field gives you sharper lineups than a giant one modeling a contest you never entered. Pool size is a generation input, so changing it forces a full re-run; set it before you build.

When should I use the ROI or player boosts? Only when you have information the model does not: confirmed late news, a batting-order change, or a leverage read you will stand behind. Boost two or three players at most, in small nudges, and re-favorite to see the effect before adding more, with no re-run needed.

What is the difference between field ownership and my exposure? Field ownership is how the simulated opponents build, so you adjust it to make the field realistic. Your exposure is how often your own lineups use a player. Fix the field first, because leverage is measured against it, then shape your pool.

Should I use these Sims settings for cash games? No. The leverage, exposure, and boost tuning in this guide is for tournaments (GPPs). For cash (double-ups and 50/50s) you only need to beat about half the field, so build your pool as usual but sort by raw projection and take the highest-floor build rather than choosing by simulated tournament ROI.

Ready To Tune Your Own Slate?

The Stokastic Sims build your MLB DFS lineup pool, simulate it against a modeled tournament field tens of thousands of times, and hand you the builds with the best simulated ROI, plus the exposure, stack, and ROI-boost controls covered above. They live on the Data + Sims and Sims MAX tiers, and code SIMTUNE10 takes 10% off your first payment. Try the settings on a live MLB slate: tune your first slate with 10% off. New to the tool? Start free with the DFS Sims and pull a live board from the MLB DataHub.