When one of your sleepers performs well in spring training, an unfortunate side effect is that he becomes everybody's sleeper, all but ensuring you'll never get to draft him again.
The Rays' Alex Cobb is that guy for me this year. I don't think he has ace potential, but I think he's good enough to start every week even in shallower leagues. He allowed three earned runs or fewer in 14 of his final 15 starts last year -- and with a good enough strikeout rate to distance himself from guys like Mark Buehrle and Jason Vargas.
But then manager Joe Maddon had to draw attention to him by awarding him the fourth spot in the rotation before spring training even began, and then Cobb had to go and strike out 28 batters in 25 2/3 innings while compiling a 2.81 ERA and 0.94 WHIP.
All good signs, but not good enough for me to value Cobb over Brett Anderson and Josh Beckett, as some people now do.