Stewart is a very highly touted pitching prospect, third round pick in 08 that is absolutely lighting up the minors.
http://www.rotowire.com/baseball/player.htm?id=10490
Zach Stewart pitched two scoreless innings in relief to get the save. That's 9 2/3 innings in Louisville so far without giving up an earned run, and he hasn't given one up since June 24th, when he was a Mudcat. In his 89 total innings (split between 3 levels), his ERA is a stellar 1.62.