MLB DFS Research Walkthrough: When the Lineup Changes
MLB DFS research turns on the batting order. A hitter's projection assumes a spot in the lineup, and that spot is often not confirmed until a few hours before first pitch. This walkthrough follows two made-up hitters from their first projections, through a confirmed lineup that moves one of them, to the checks to run before lock.
The players and the numbers are invented to show the method.
1. Set the site and slate
Open the MLB tool and choose DraftKings or FanDuel and the slate you are entering. The two sites score and price differently, and FanDuel allows at most four hitters from one team.
2. Take a baseline
Field projects for 10.2 points batting second against a right-handed starter, at a salary of 4,200. His teammate River projects for 8.8 while batting third. Together that is 19.0. The lineup is not confirmed yet, so write "batting second, assumed" beside Field's number.
3. The lineup is posted
Field is batting seventh. An updated projection has him at 8.1. River is unchanged at 8.8, so the pair is now 16.9, down 2.1.
Example note: Field assumed second, confirmed seventh. 10.2 to 8.1. Pair 19.0 to 16.9. River unchanged. Same site and slate.
The reason is simple. A hitter lower in the order comes to the plate less often, and each trip is a chance to score. Check his value again at the current salary; the lower projection changes that comparison.
4. Don't add two projections and call it a stack
19.0, or 16.9, is two averages added together. It tells you nothing about how the pair scores together, and that is the point of stacking: when one teammate reaches base and the next drives him in, both score from the same play. Two hitters five spots apart in the order share fewer of those plays than two who bat back to back.
The change may also affect how Field and River score together. Do not infer its size from the 2.1-point projection change. Check whether your model represents the confirmed order and compare its joint outcomes; a sum of projections cannot show the effect.
5. Run it again and rebuild
A simulation or a portfolio from before the lineup was posted used the old order. Run it again. If you are building a full set, the field guide covers it: load your contest entries CSV on the Lineups tab, open Portfolio, choose a model and build. For DraftKings you can set a mix of five-man, four-man and scattered stacks. FanDuel still has the four-hitter team limit. Before you export, check that the number built matches the number you asked for and that the stacks are the ones you meant.
6. If someone is scratched after you enter
Late Swap handles it for DraftKings entries. Import your current entries CSV, and it replaces inactive players while leaving your other players, and any player whose game has locked, in place. It gives you a CSV. You upload that to DraftKings yourself and confirm the change there.
Where to see it
Squirt Squad covers matchup screens and projection matrices. Squirt Squad VIP adds SPAGS projections, exports and simulation results. Apex adds lineup browsing and the Portfolio Builder for NFL and MLB. Compare memberships. Projections and simulation results are model outputs, not a promise of results.
Related: NBA DFS research walkthrough · What to do when a player is ruled out