What if the Red Sox had kept Mookie Betts?

Betts was a year from free agency and had just agreed to a record $27 million arbitration salary when Boston moved him. On February 9, 2020, the Red Sox sent him and David Price to the Dodgers for Alex Verdugo, Jeter Downs and Connor Wong. The later reporting was clear that ownership never forced it: the reset was the front office's call. What followed in Boston was one championship-less stretch, and three years later the payroll logic behind the trade ended with the club dealing Rafael Devers.

The counterfactual is unusually clean, because Betts himself closed the door on it. He signed a 12-year, $365 million extension with the Dodgers in July 2020, and that summer he said he would have accepted that same deal in Boston. So the question is not whether he would have stayed. It is what the six seasons since were worth in a Red Sox uniform.

We replayed his real 2020 through 2025 Dodger seasons in Boston: the 60-game sprint, the MVP-level years, the injury-shortened ones, all of it, translated to the American League and Fenway Park. Fifty runs, every game played out, his real playing time kept. One honesty receipt before the numbers: this engine, replaying him on his real Dodger path, lands a median of 130 home runs against his real 152, about 14.5 percent light. Every number below is that engine's conservative floor.

The real 2020 Red Sox went 24-36 and finished last in the division in a season that only lasted 60 games. With Betts added to that roster, the 50 runs give Boston a median of 32 wins, still under .500, and no title in the median run. One player does not rescue a pitching staff in a sprint.

This is also the only season the two branches of the argument share. If the Red Sox had kept him and let him walk that winter, this is the year they got. The comp pick, the Verdugo years, the shed Price money and the chain to Devers are the rest of that ledger, and no engine can price them. The rest of this page prices only the other branch: he stays, the way he said he would have.

In the real world Boston went 92-70 in 2021 and reached the ALCS, then 78-84 twice. In these runs the 2021 club wins a median of 94 games, and in the median run it goes 105-58 and wins the World Series with Betts batting at the top of the order. Across all 50 runs, Boston wins a title in 66 percent of them at least once, and in 32 percent at least twice.

The 2022 and 2023 seasons are the quieter finding. The median club wins 86 and 90 games those years against the real 78-78, and the runs split on October: Boston reaches the playoffs in 33 of the 50 runs in 2022 and 43 of 50 in 2023, because the sim does not hand out wins, the rest of the league plays too. Contention is the difference here, not a dynasty: across the six seasons Boston makes the playoffs in a median of five of them, against the real two.

By 2024 the real Red Sox had settled at 81-81, and the 2025 club at 89-73 reached the playoffs without him. In the runs, those seasons carry his late-prime bat translated into Fenway: a median of 17 home runs in 2024, a year his real wrist injury held him to 116 games in Los Angeles, and the engine replays that short season short.

Add the six seasons up and the median Boston-with-Betts club wins 487 games, against the real club's 442. Read the gap as direction, not magnitude: the engine's league scores fewer runs than the real one, so both sides of that comparison carry the same distortion. It points where the argument always did. The reset bought prospect depth. It did not buy these six seasons.

In Boston, the median run gives Betts 137 career home runs across the six seasons, against the 152 he really hit in Los Angeles, and one World Series title for the club, with 66 percent of runs producing at least one. The subject numbers are the reliable receipts here; the team numbers tilt with the engine's whole league.

The flip side is the one Los Angeles fans will check first. In the 50 runs without him, the Dodgers still reach the playoffs a median of five times, still win a pennant in the median run, but land zero titles in the median, and at least one title in only 32 percent of runs. The real Dodgers with Betts won three of the last six World Series. The engine is saying something defensible and something careful at once: that franchise contends without him, and the October difference is the part a single player actually moves.

The gate receipt stays the headline: this engine replays Mookie Betts 14.5 percent light on home runs, against a Ruth-era anchor of 1.6 percent under, so treat his Boston line as a floor. The Boston numbers still clear the bar the argument needs. He said he would have taken the deal. The engine says the deal was worth taking.