I think you could make a compelling argument that the cumulative pounding that Burrow has taken thus far in his career exceeds what Allen has taken, despite Allen playing a much more physical style. Burrow hangs in to the last second and gets blasted a lot, and he has to because of his line play. Yesterday may have been a routine tackle, but at 28 years old, he's probably absorbed the abuse that someone in their mid 30s at the position would have taken, so he's probably more likely to get injured as a result at this point.