Every SaberSim projection comes from play-by-play game simulations.
For each game on the slate, SaberSim simulates the game from the first play to the last, thousands of times. Each run is a full game script with its own play calling, scoring, and game flow, and every player gets a fantasy score in every run. The projection you see is the average of a player's scores across all of them. The percentiles next to it show the spread: the 25th percentile is a player's floor, the 50th is their median, and the 85th to 99th is their ceiling.
Because every player's score comes from the same simulated game, the relationships between players are built in. When a QB throws for 400 yards in a simulation, his receivers score in that same simulation. That's why SaberSim can build correlated lineups without stacking rules.
We built the simulator to model strategy, coaching tendencies, matchups, and the game clock. The simulations re-run when news breaks, so projections update within minutes of an injury or lineup change.