It's because of the 75-man roster limit. Just looking at the Chiefs there's quite a few guys that have good shots at making the team that aren't on their roster. The thing the roster limits do as well is force them to change guys positions to fit within the roster requirements. They really, really need to get up to 90 or even 100 player roster limits so all these guys can make it into the game. Or at the very least up the free agent limit and have them all in free agency.