MLB DFS Post-Contest Simulator: How To Review Your Lineups

The MLB DFS Post-Contest Simulator is the Stokastic tool that separates players who improve from players who just keep firing lineups. Most players do the same thing when a slate ends: they glance at the profit-loss number, feel good or bad about it, and fire again tomorrow. That is the fastest way to stay precisely as good as you are right now. Winning at baseball DFS over a full season is not only about building lineups before lock. It is about taking every lineup you entered apart afterward, against the whole field, so you can see what actually worked and what quietly leaked money. And the single most common thing this tool reveals about the players finishing at the top is a construction habit almost nobody copies. We will get to that.

In Summary

• It Is A Review Tool, Not A Build Tool. After a DraftKings contest ends, it re-simulates every lineup in the field using the actual ownership and our projections, so you can grade your entries against everyone else's instead of only reading last night's cash number.
• Sim ROI Is The Honest Verdict. Actual ROI is one night of variance; Sim ROI is how good the process was across thousands of outcomes, and it is the number you want trending up.
• Set It Up Like A Contest Lookup: baseball, DraftKings (FanDuel does not publish the CSVs), the date, the slate, and the exact contest, then your username to pull your lineups.
• The Player, Stack, And Lineup Views Find Your Leaks: where you were over- or under-exposed versus the field, which stacks graded out best and worst, and which of your builds were the sharpest and the shakiest in the entire contest.
• The Winners Share One Habit: pull the field, sort by Sim ROI, and study the max-entry players near the top. On the slate in the walkthrough, that habit was overwhelmingly five-man stacks.

Watch The Video

Here is the full walkthrough this article is built from, run on a real MLB slate. Watch on YouTube.

Why Post-Contest Review Is The Step Most Players Skip

A winning MLB DFS process has two halves, and most players only do the first. The front half is building good lineups, the job the MLB DFS Sims handle before lock, generating your builds and controlling your exposures. The back half is the review: taking a finished slate apart so tomorrow's lineups are sharper. That back half is where the Post-Contest Simulator lives, and it is the half almost everyone skips.

The tool takes a contest that has already been decided and re-simulates every lineup in it. And "actual results" here does not mean how many fantasy points each hitter happened to score. It means the actual ownership of every player, the actual lineup construction the field used, and how all of that was expected to perform against our projections and sims. The point is not the single result that landed, because one slate is mostly noise. What matters is the expected value of what you and the field played, the difference between a good process and a lucky night. If you are still fuzzy on why simulated outcomes beat a single-point projection, our Sims vs optimizers breakdown covers the logic.

Pull Up The Contest You Want To Analyze

You will find the Post-Contest Simulator inside the suite of sims tools, over on the right with the rest of the data. Setting it up mirrors looking up any contest, so get these right before you run anything:

• Sport And Site. Select baseball, and set the site to DraftKings. FanDuel does not make its contest CSVs available, so post-contest review is a DraftKings-only exercise for now.
• Date And Contest. Pick the slate date, then the specific contest, such as the $3 150-max on DraftKings, the kind of large-field GPP a lot of players fire.
• Username. Type in your own username to pull your lineups. You can leave it blank to study a contest you did not even play, or add an opponent's username to compare your lineups head-to-head against theirs.

Then run the contest simulation. Everything below is built from that one screen.

Read Your Contest-Level Numbers First

The top of the results shows a summary row for your entries. Here is what the 150-max entry in the walkthrough looked like:

Metric	Walkthrough value	What it tells you
Lineups Played	150	Entry volume for the contest
Dupes Per Lineup	Minimal	How often the field landed on your exact build (rarely a concern on large MLB slates)
Sim Lineup ROI	7.7%	Expected ROI of your lineups across the sims
Actual Lineup ROI	0.2%	What the lineups actually returned that night
Sim Fantasy Points	97 avg	Projected points per lineup
Actual Fantasy Points	107 avg	Points the lineups actually scored
Ownership Sum	115.7%	Combined ownership packed into a typical lineup

The row worth sitting with is the ROI split: a 7.7% Sim ROI against a 0.2% actual, in the walkthrough's words, "a very neutral slate." The lineups outscored their projection (107 actual points versus 97 simulated) yet still returned almost nothing, which is exactly the kind of gap that tells you the story was leverage and construction, not raw points. Ownership sum is the quickest tell for that: it measures how much combined chalk you stacked into a lineup, the difference between playing the field and playing away from it.

A Worked Example: Reading The Player ROI View

This is the view that turns a fuzzy "I ran bad" into a specific leak. For every player on the slate you get their field ownership, their sim ROI, and their actual ROI. Once you click your own name, you also see your ROI and your ownership on each of them.

Work one example all the way through, because it is the whole method in miniature. The best sim ROI of any player on this slate belonged to Jake Rogers, the Detroit Tigers catcher. The sims valued him above anyone on the board, and the field played him just 4.3% of the time: the exact shape of a leverage play, huge expected value at almost no ownership. And he cashed, too. Lineups with Rogers in them posted a 217.3% actual ROI, the real result rather than the projection. The entrant had Rogers in 8% of lineups, roughly double the field, so he was correctly overweight the single best play on the board. Yet his own Rogers lineups returned only 29.2% ROI. Right player, and the gap suggests the construction around him, not the pick itself, was the leak. That is exactly what this view exposes, and you can sort it by every position to run the same read on your outfield, your corners, and the rest.

Hold onto that 4.3% number. It comes back.

Close the loop on your MLB process. The Post-Contest Simulator ships with the Stokastic MLB Sims, alongside the Contest Sims that build your lineups, projections, and ownership. New here? Code POSTSIMMLB10 takes 10% off your first payment so you can grade every slate against the field: Start with the Stokastic MLB Sims.

Use The Stack ROI View To Grade Your Construction

Baseball is a stacking game, so the stack view is where MLB post-contest review earns its keep. It shows the expected ROI of every stack you built. In the walkthrough, the Cincinnati Reds stacks graded at a 28.9% expected ROI and the Detroit Tigers stacks at 26.4%, the good side of the ledger. The bad side was just as clear: the Braves lineups carried a -13% expected ROI and the Red Sox lineups -12.5%. That contrast is the actionable part. You are not asking "did I win," you are asking which teams the sims wanted more of and which ones you should have faded.

Drop down to stack types and it gets sharper still. Same team core, wildly different construction, wildly different expected value:

Stack Type	Sim ROI (walkthrough)
5-3	+41.3%
5-1-1	-6.9%
5-2-1	-23.8%

The 5-3 builds at +41.3% were the sharpest construction on the board by a wide margin, while the 5-2-1 shape bled at -23.8% off that same five-man base. That split is the tell that stacking is not just which team, but how you spread the rest of the roster around it. Then flip to the whole field and the tool tells you which teams were simply the right places to be: on this slate the Detroit Tigers and Pittsburgh Pirates were the best overall stacks, while the Baltimore Orioles, Atlanta Braves, and Kansas City Royals carried the most negative expected ROI in the contest. If you want to translate those reads into how you build the next night, our MLB DFS stacking guide is the companion piece.

Use The Lineup ROI View To Diagnose Bad Builds

Switch to the lineup view and you can rank every single lineup in the GPP by expected ROI, then narrow to just your own. Each one carries its full metrics: where it finished, how often it was duplicated, salary used, actual points, simulated points, and ownership.

This is where variance gets honest. The best-projected lineup in the entire field belonged to a user named Dane 09444 at a 100.9% Sim ROI, built on Paul Skenes and Nestor Cortes on the mound. The entrant's own top lineup ran the same Skenes and Cortes pitching pair behind a five-man Tigers stack fronted by Jake Rogers. At the other end, his worst build graded at a -36% Sim ROI on a Framber Valdez and Reese Olson arm pairing. The habit to build here is filtering by dupes and by your lowest Sim ROI lineups, then asking what those builds had in common, because that is the combination to strip out of the sims before you ever enter it again.

Study The Winners: The Five-Man-Stack Payoff

Now the forward promise. Open the user ROI view, filter to everyone who entered 150 lineups, and you are measuring yourself only against players who faced the exact same decision you did. The top name among the 150-max entrants was JNW1129, with the highest simulated ROI in that tier at 22.9%, and a 91.8% actual ROI, nearly doubling his money on the contest.

Click his username and study the build. Of his 150 lineups, roughly 125 were five-man stacks, and that is the habit teased at the top. It is the pattern that keeps surfacing in the post-contest sims: the best overall lineups are, over and over, five-man stacks. Four-man stacks can win, but the top of the board is stacked with fives, which is why the players who keep finishing near the top point their Contest Sims at the best five-man stacks a slate offers. Across his 150 lineups he ran a heavily concentrated pitching core, 76% Paul Skenes and 29% Nick Lodolo, and his hitters leaned on the Reds and the Tigers, the same two teams whose stacks had graded out best in the walkthrough's own stack ROI earlier (Cincinnati at 28.9%, Detroit at 26.4%), with the Tigers also topping the field-wide best-stacks list. And remember Jake Rogers at 4.3% owned: the players near the top of this contest were living in exactly those low-owned, high-EV Tigers and Reds bats while the field crowded elsewhere. Reverse-engineering that (which players the winners attack, how much ownership they absorb, how they build a core) is one of the fastest ways to improve, and almost nobody does it.

Feed What You Learn Back Into Your Builds

The Post-Contest Simulator only pays off if the review changes what you do next. Make it concrete. If the review turns up a Jake-Rogers-type play (a bat the sims loved at 4.3% ownership that you barely touched), the rule you write for yourself is to hunt low-owned, high-Sim-ROI hitters harder. If your 5-2-1 shapes bled at -23.8% while your 5-3 builds returned +41.3%, that becomes a construction filter you apply in the MLB DFS Sims before you enter, not a regret after. You do not even have to have played a contest to learn this way; pull any GPP, see what the field did, and you may decide a softer contest suits you better than the one you have been firing. Newer to the fundamentals underneath all of this? Start with how to win at MLB DFS.

Frequently Asked Questions

What is the MLB DFS Post-Contest Simulator? It is a Stokastic tool that, after a DraftKings baseball contest ends, re-simulates every lineup in the field using the actual ownership and our projections, so you can grade your own entries against everyone else's on Sim ROI, ownership, stacks, and dupes. It turns a finished slate into a review that makes your next builds better.

What is the difference between Sim ROI and actual ROI? Actual ROI is what your lineup returned in the one contest that happened. Sim ROI is the expected ROI across thousands of simulated outcomes, so it measures how good the process was rather than how one night broke. A lineup can spike on a low Sim ROI or lose with a great one, and both are variance. Over a season, you want to be on the high-Sim-ROI builds.

Can I use it for FanDuel MLB contests? Not currently. FanDuel does not make its contest CSVs available, so the post-contest sims work for DraftKings baseball contests only.

How do I compare myself to other players? Enter your username to pull your lineups, sort the field by Sim ROI, and filter to your own entry volume, for example only other 150-max players. You can also type a specific opponent's username to compare exposures and builds head-to-head.

Which Stokastic package includes the Post-Contest Simulator? It comes with the Stokastic MLB Sims, alongside the Contest Sims that build your lineups, projections, and ownership projections.

Compound Your Edge, One Slate At A Time

Zoom back out and the players at the top of that contest were not doing anything mysterious. They lived on the low-owned bats the sims loved, built them into five-man stacks, and got the construction right, and the Post-Contest Simulator is where all of that becomes visible after the fact. Grade the lineups on Sim ROI, isolate the leaks in your exposure and your stacks, study the max-entry builds that keep finishing at the top, and carry the fix into tomorrow's Sims. The rest of the field will keep glancing at its profit-loss and moving on. Do the review, and you pull away from them one slate at a time.

Ready to close the loop on your MLB DFS process? The Post-Contest Simulator comes with the Stokastic MLB Sims, next to the Contest Sims, projections, and ownership. Code POSTSIMMLB10 takes 10% off your first payment: Get the Stokastic MLB Sims. You can also try the free DFS Sims first.