Prospect of the Day: Robbie Erlin, LHP, San Diego Padres

The San Diego Padres promoted left-handed pitcher Robbie Erlin to the major leagues yesterday. Although Erlin's role on the staff may be fluid in the short run, in the long run I think he projects as a regular starter.

Erlin was drafted by the Texas Rangers in the third round in 2009, from high school in Scotts Valley, California. He was considered one of the most polished prep pitchers available that year, but his small size and a Cal Poly scholarship kept him out of the first two rounds. He made his pro debut in the Arizona Rookie League that summer, pitching five innings, fanning nine, and looking extremely sharp overall.

This got him assigned directly to Low-A to open 2010 and he made the most of it, posting a 2.12 ERA with a spectacular 125/17 K/BB ratio in 115 innings for Hickory in the South Atlantic League, allowing just 89 hits, emerging as one of Texas' top prospects. He maintained this status in 2011, thriving in the High-A Carolina League for Myrtle Beach (2.14 ERA, 62/5 K/BB in 55 innings, just 25 hits) and holding his own in Double-A (4.32 ERA in 67 innings for Frisco, but with a 61/7 K/BB).

The Rangers flipped him to the Padres at the trade deadline along with fellow prospect Joe Wieland for reliever Mike Adams. He ran off six outstanding starts for San Antonio after the trade (1.38 ERA, 31/4 K/BB in 26 innings).

2012 brought mixed news. He was excellent when on the mound (2.92 ERA with a 72/14 K/BB in 52 innings for San Antonio) but missed three months of action with elbow tendinitis. He rehabbed properly and looked excellent in the Arizona Fall League (2.28 ERA, 31/6 K/BB in 24 innings). He's made three starts in Triple-A this spring with adequate results and struggled with his command in his last start, walking three in five innings. However, with the totality of his track record, he's certainly worthy of a long look with the major league staff in need of an arm.

Erlin is 5-11, 190 and doesn't have plus velocity, working at 88-90 MPH with occasional 92 readings. The fastball plays up due to the contrast with his outstanding curveball and above-average changeup. He'll mix in some cutters and sliders, giving him a diverse arsenal. He is generally a fly ball pitcher and there's some concern that he could be gopher-vulnerable in the major leagues, though his hatred for walks helps contain home run damage and his home park will help him. He's highly competitive and his pitching sense is very advanced.

Assuming no further elbow problems, Erlin profiles well as a strike-throwing number four starter at worst, and possibly a number three if he fully maxes out his talents. I think the key thing to watch right now will be his K/BB ratio. Will major league hitters prove as vulnerable as minor league hitters to his approach, or will they be less vulnerable to Erlin's tricks? It may take him some time to adjust, but his sabermetric case is strong, and scouts are generally more favorable towards Erlin than they are to the average finesse pitcher.