Two words: Injury prone
unless olly has a pattern of having kids around who cause him injury, then he cannot be blamed for being injury prone. injury prone refers to a physical condition, or style of play, that results in repeated and similar types of injuries.
no one is "prone" being tripped by little kids. 
Good luck trying to explain that to the snickering set on here...what a lame bunch of alleged Celtics fans!
Injury prone is not that simple. If a player lacks balance and has weak ankles or knees, that player is far more likely to be injured and is thus injury prone.
Also, Olynyk seems to have a pretty low pain threshold because seemingly small injuries completely destroy his game.
I think it is completely fair to label Kelly Injury prone. Perhaps fragile is more appropriate.