How did he get here?: Signed as undrafted free agent prior to 2008 season
Stats: 5'11", 179 lbs, Throws: Right
Age as of April 1, 2011: 20
Previous Years (2008-09)
This was Del Rio's first year in the States, having spent 2008 in the VSL and 2009 in the DSL, and his numbers suffered accordingly - but not so much that we question his ability. For one thing, he pitched better than his 1-7 record would indicate, and it's common for a foreign-born player to have a rough first season in the States (I keep meaning to do a survey of this, but, um, haven't.).
Basically what happened is that he got hit hard, particularly in August, when opposing batters hit .361 against him in five starts, including his last start of the season (August 28), when the GCL Cardinals rocked him for 15H/7ER in 6IP. Your numbers - especially in 53.1IP - don't recover easily from that.
What went right?
Walks, or the lack thereof. He lead the starters with the fewest walks allowed in 2010. In three minor-league seasons, Del Rio has walked just a touch under two batters per nine innings, and walked right at 2.0 batters/9 this season. Given his low walks and low strikeout rate, that means he pounds the zone pretty hard, and the bats just caught up with him this season.
Pitching at home. In four home starts, Del Rio was 0-3, but with a 2.35 ERA/0.91 WHIP, with 19K:3BB. His BAA was also .209 at home, compared to pitching on the road (7.86 ERA/1.86 WHIP, .370 BAA).
What went wrong?
We've already talked about the hitability of his pitches, so he's going to need to make the ball more elusive. But he was pretty unlucky, getting tagged with a .352 BABIP this season.
Throwing against lefties. Righties hit .284 against Del Rio, which isn't great, but it certainly isn't the 22 hits lefties tagged him for in 39 outs, hitting .393. That said, only four of the 72 hits opposing batters got off Del Rio went out of the park.
Neutralized for luck, Del Rio's FIP was 3.71, so it seems like he should be able to make some strides in 2011 - maybe in Tri-City.