On Monday, the Washington Nationals top prospect, SP Jordan Zimmermann, made his major league debut two years after being selected in the 2nd round of the 2007 draft. To sum up his potential, this is what Baseball America said about him:
...the rare pitcher who projects to have four average or better offerings in the majors...His athleticsim helps him field his position well, hold runners, handle the bat and bunt well. An intense competitor, he's serious about his craft...
Jonathan Sanchez of the San Francisco Giants was touted as a potential slepper in 2009 following his first full season in the rotation which saw him strike out 157 batters in 158 innings. Unfortunately, he did that with a 5.01 ERA and 1.45 WHIP.
I think Zimmermann will garnish the most questions about whether he should be picked up. Sanchez represents the type of pitcher who is likely to be cut to do so in your typical mixed league.