That is why in practice you will always hear coaches screaming "Stay up, Stay up"!..When guys go to the ground, they can roll the big guys up. That is exactly what happened to Dom. Poor guy gets rolled up while pulling. He is the one guy that would be hard to replace. 1st, he most likely makes all the calls when he walks up to the LOS. He most likely is the O-Lines QB. Gets them redirected and makes all the calls. (most good center's make all the calls). It also can screw up QB/Center exchange when you lose your starting Center.
Don't know enough about his back up. They will adapt, but QB/Center exchange is vital not only with the QB under the Center, but even more importantly when in the Gun. The ball placement on the snap is crucial so the QB can keep his eyes down field and on his keys. When the ball is snapped too low, or too high, too far right, too far left, the QB loses precious time having to locate the ball and then redirect his vision back to his read. Remember, you only have about 3.4 seconds on average to get the ball off, so any loss of time on a snap, can really hurt you.