Well, first of all I can think of other pitching prospects that are more likely to get hurt and I don't see how you can say it's a fact that he the most likely. He has nothing on his record that says he will, not saying he won't ... but it's less likely. Also minor leaguers don't play 6 months, they play 5 months which is basically the same as college baseball if you make it to the CWS. Yes college doesn't play as many games, but pitchers pitch more often (and go deeper in games in Pelfrey's case) making up for that.
Pelfrey last year pitched 140 innings in college. Look at other top pitching prospects who didn't get to much extra starts in the majors: Billingsley 146, Zumaya 151, Petit 133, Reyes 129 (13 MLB IP), Verlander 119 (11 MLB IP).