(or any sport, i guess)
is it an exact science?
mix of all three?
do they just say, 'well, he hasn't played for a bit, he probably shouldn't until we've made him run up the big hill a few times'
how can someone categorically say that someone is/isn't ready to take part in a professional game?
what is the process?
surely, you only really know once they've tried to play.