On Sunday, Pro Bowl left tackle Joe Staley had played 37 plays when he fell prey to a concussion on a blindside hit from Giants safety Stevie Brown. He would not play another down against New York. Stepping into his spot was right guard Alex Boone.
Like Staley, Boone had been a part of all 37 snaps to this point in the game at his normal position. Boone did well enough at left tackle that Coach Harbaugh kept him in the game even when it was out of hand. Filling in for Boone at guard was Leonard Davis. Davis participated in all 24 snaps to close out the game after being on the bench for two and half quarters.
It's unclear at this point if Staley will be available for this Thursday's game against the Seattle Seahawks. Also not known at this time is the position on the field Boone and Davis will be playing (or not playing). This is Staley's second concussion since December. He was able to play the game following that concussion, but that's all moot until he passes the multiple concussion tests mandated by the NFL.