It's definitely all comps, they have 69 games in that column. 'Day's in a season' gives it away. PL started mid September, which is a full 30 days later than normal, whereas Community Shield was late August, which is potnetially only 15 days later.
I'm also guessing it doesn't factor in that players are going off and playing 3 games during the international break rather than 2.
Either way, I think injuries are already up 30%. Could be a coincidence, but it's there. And we haven't even got to the nightmarish xmas period.