Injuries are a big problem... for some teams. Me, I don't usually have any problem. I don't hardly ever go to full out attack/defend/tackle, I keep the physical stats of my guys at or above their main skills, they are near fully rested at match time, and have the best turf I can. I don't use a lot of arrows.

I do notice sometimes when I play away at tiny stadium, more injury. If I have done a bunch of training the next couple matches those guys are more prone to get hurt, too. I have back up players for most positions (admittedly not GK, but those teams have to hold 15 reds at all times) and try to let the broken guys sit out, even a match AFTER they heal.