10.  Sean O’Sullivan, rhsp   

Birthday: 09/87    Height: 6’1”    Weight: 220

2008 stat line in High A   – 158 innings    ERA: 4.73   K/9: 0.70   K/BB = 2.22  GO/AO = 1.29

Sean O’Sullivan - or “Nacho” to his teammates - won consecutive ERA titles in the Pioneer and Midwest Leagues while still a teen, prompting high expectations for his performance entering 2008. Baseball America and John Sickles both ranked him the Halos’ fifth best prospect last winter. An Angels message board and futureangels.com were even more bullish, penciling him in at fourth. Projections ranged from back of the rotation innings eater to the next coming of Derek Lowe. 

But Sean stumbled out of the gate in the California League, yielding a 6.35 ERA through the All Star break. Sean’s walk rate worsened by a third over the previous year, from 2.3 BB/9 to 3.66 BB/9; his ground ball to fly ball ratio declined from 1.27 to 1.18; and his home runs allowed per 9 crept up slightly. For the first time in his young career, he gave up more than a hit an inning.  Interestingly, his decline in performance accompanied the best k-rate of his career, which increased to 0.78 K/inning from April to June.  Perhaps that correlation was a statistical blip, or perhaps it’s an indicator that Sean was consciously chasing the strikeout to the detriment of his overall performance.

By July 1st last season, Sean’s career appeared to be stalling, just another victim of the California League’s hitter-friendly parks. The poor first half also kept Sean from reappearing in most top ten Halos’ prospects lists this winter. 

Fortunately, Sean pulled it together in July and turned in a second half that was much more in line with his two previous seasons. His control improved considerably, with his K/BB climbing from a weak 1.93 to a far more promising 2.65, despite a slight decrease in strikeout rate. He did a better job keeping the ball down in the zone, leading to fewer home runs and a more healthy 1.40 ground ball to fly ball ratio.  Lastly, opposing hitters lost 40 points of batting average against him.  These improvements added up to a 3.38 ERA from July to September, an impressive showing for a twenty-year old in the California League and the reason why he still ranks among my top ten Halos’ prospects. 

When he’s on, Sean exhibits plus command of a 87-91 mph fastball, curve, slider, change up, and a two-seamer. While scouts graded none of these offerings as plus plus - in other words, Sean lacks the “out pitch” necessary to rack up K’s - they projected that he could continue to advance due to his ability to keep batters off balance while efficiently pitching to contact. 

A weak K-rate and good-but-not-great ground ball ratio mean that Sean has to do everything else right to be successful.  He retains some control over what hitters do against him - scouts have raved about his ability to change speeds, his pitch selection and, most importantly, his command.  But by pitching to contact, he’s heavily exposed to the ebb and flow of luck on balls in play, and will therefore have days, weeks, and even months when the hits just keep falling.  His ability to adjust and work through those periods will determine what kind of his career he has. Fortunately, Sean has a track record of successfully managing just such adjustments - as a high school junior, he first gained national attention by blowing hitters away with a 95 mph fastball.  While those days are probably gone for good, Sean’s ability to evolve bodes well for his future. 

Projection: In the short term, Nacho is likely headed to the Halos’ AA affiliate in Arkansas, where he will be among the youngest prospects in his league for the fourth season in a row.  Over the long run, a good comp is Jon Garland, another durable, low strike-out, moderate-ground-ball-inducing control artist. IF Sean hits his ceiling, he could pitch a few MLB seasons where his ERA touches the high 3’s; most seasons would be more in line with the league average, though he’s capable of eating a lot of innings. While Sean’s mediocre k-rate means that he has a lower ceiling than most of the pitchers further down on this list, the combination of track-record, health, and overall make-up indicate to me that he has better a shot at hitting that ceiling.  

Tomorrow's prospect of the day will be Luis "Lucho" Jiminez.  We've got some great nicknames in the pipeline....