I never said it occurred in a vacuum. Probably half the team is nursing an injury of some sort. You can't adjust and compensate for everything. If a RB is cleared to play, the coaches should assume he can be asked to carry the ball, be targeted for passes, and block when required. Lacy wasn't asked to do anything other than that. It's not up to the coach to second guess the medical staff.
Of course they took a chance, just like they did with Cobb, Adams, Bakhtiari and others last year. Just like Rodgers two years ago. Matthews countless times. Lacy other times, too. Lang now. Bulaga many times. Randall this year. Sitton for several years. There was nothing uniquely special about Lacy's situation. In fact, it was almost routine. They had a plan for how to proceed without him.