Contreras's Hamstring Strain: How Much Does It Hurt Boston?
With no in-house replacement at first base, Boston loses its third-most valuable hitter for nine games — though a soft schedule against sub-.500 teams softens the blow.
Published: · Figures as of September 1, 2026
Asked: How much does losing Willson Contreras hurt Boston?
Contreras's hamstring strain leaves Boston with no first baseman
Willson Contreras is genuinely out — not a hypothetical. He was placed on the injury report on 2026-08-31 with a left hamstring strain, expected back 2026-09-11, which lines up to a stretch of nine scheduled games missed (9/1-9/2 vs. Seattle, 9/3-9/6 at Baltimore, 9/7-9/9 vs. the Angels) before he's projected to return against Kansas City on 9/11.
What Boston loses at the plate
Contreras has been Boston's best power source this season: he leads the team in home runs (26) and RBI (79) among all batters, and his rate numbers are well clear of league norms — a .356 on-base percentage against a league-wide .320, a .516 slugging percentage against .400, and an .872 OPS against the pooled league figure of .720 (about .15 higher, and roughly 1.6 standard deviations above the .730 mean for qualified hitters). His 4.38 WAR ranks third on the roster, just behind Ceddanne Rafaela (5.6) and Wilyer Abreu (5.56).
| Player | WAR (WAR) |
|---|---|
| Rafaela | 5.6 |
| Abreu | 5.56 |
| Contreras | 4.38 |
| Durbin | 3.48 |
| Mead | 1.98 |
That value is almost entirely the bat. His fielding at first is below replacement level (-0.56 dWAR) even though his fielding percentage is clean (.995) — so this is a lineup loss, not a defensive one.
No internal replacement on the books
Contreras has played first base in all but one of Boston's 138 games this season — he hasn't shared the position with anyone on the current roster. Triston Casas, a natural first baseman, is on the roster as an "arrival" but hasn't appeared in a game since May 2025 and isn't on the current injury report, so there's no data explaining his absence or confirming he's ready to step in. Whoever covers first base over these nine games will most likely be an improvised fit rather than an established option — that part is a real hole, not just a hitting downgrade.
It's not an isolated absence
Boston is also without Masataka Yoshida (hamstring, projected back 9/22), Marcelo Mayer (forearm fracture, 9/6) and Curtis Mead (wrist fracture, 9/15) right now. Contreras going down overlaps with three other injured regulars, which is relevant context for how much bench and depth Boston has to work with while replacing him specifically.
The cushion: a soft schedule
The nine games Contreras will miss come against Seattle (.464), Baltimore (.500) and the Angels (.384) — all currently sub-.500 clubs. That doesn't erase the loss of a .872-OPS bat, but it's a softer stretch of schedule than Boston's average opponent this season (season-long opponent win rate around .504), which limits the downside somewhat.
Why it matters right now
Boston is 75-63, 8th of 30 in the league and 3rd in the AL East, 7.5 games back in the division — squarely in wild-card territory in early September. Losing a top-three hitter by WAR for roughly a week and a half, with no ready-made replacement, is a real dent to a team still fighting for playoff position, even if a favorable schedule takes some of the edge off.
Confidence: High on the size of Contreras's offensive value and the absence of a 2026 replacement at first base — those are direct from this season's stat lines. Lower confidence on exactly who fills in for those nine games and how that lineup performs, since nothing in the data yet shows who plays first base while he's out.