Often the guys who are in the best condition are the ones who are down with nagging injuries the most often. These guys are like highly tuned performance vehicles - when they are running well they are a sight to behold, but one little thing goes wrong and they are in the shop. They just don't "feel right", and it takes them longer to get back than some plugger.
Related, I can remember Marc Crawford getting himself in some trouble when he was coaching the Canucks when he said of Naslund, "Markus is very particular about the way he feels." Some media felt that Crawford was saying that Naslund was soft. There was definitely a bit of that, but it's more nuanced than that - again, like a lot of elite athletes, Naslund was very aware of his body and when something didn't feel quite right. Crawford, as a player, was a banging winger who scored most of his goals from in front of the crease...