Reliever Daniel Schlereth was promoted from double-A on May 29. The hard-throwing left-hander was the club’s first round draft pick (26th overall) out of the University of Arizona in the 2008 MLB amateur draft. It took the 23-year-old hurler just 25 minor league games to prove his MLB-readiness in the Diamondbacks’ eyes. During that span, he posted a 1.45 ERA and rates of 5.5 BB/9 and 11.9 K/9. Obviously, the walk rate is a concern at this point, especially with it sitting at 6.2 BB/9 in 2009 at double-A.
There are definitely some other key statistics with Schlereth’s 2009 minor league performance to date, including the nine hits allowed in 19 innings (4.3 H/9). He’s tough to hit when he gets the ball over the plate. As well, his fastball sits in the low 90s (He’s averaging 93 mph in his two MLB games) and it can touch the mid-to-upper 90s. His curveball is also very good and he’s quite confident in it, as witnessed by his willingness to throw it 43% of the time in his brief MLB career (two appearances, and innings).
In those two big league innings, Schlereth has yet to allow a run and he’s walked one while also striking out a batter. Of the outs made in play, four have come via the groundball and just one was in the air. In his pro career, Schlereth has a 55.4% groundball rate. His line-drive rate is even better at just 9.2% (His BABIP-allowed is .254).
The southpaw reliever is not going to inherit the Diamondbacks’ closer role right away, but he is definitely the odds-on-favorite to claim the job in the not-too-distant future. Current closer Chad Qualls is just 30 years old, but he’ll be a free agent after the 2010 season and the Arizona organization is one of the more cost-conscious clubs around. Qualls is also just 27-for-49 in career save opportunities, so he is not amongst the elite closers in the game (although he is 12-for-14 this season).
Schlereth is a player that deserves to be monitored over the next year or two as he should eventually begin to earn save opportunities. If Arizona wanted to be proactive, the club could start mixing in the save opportunities now, with the season already looking bleak in terms of playoff opportunities. Schlereth and Qualls could make a nice lefty-righty closer combo, with lefties hitting .325 off the latter in 2009.
Marc Hulet has been writing at FanGraphs since 2008. His work focuses on prospects and fantasy. Follow him on Twitter @marchulet.