For most 23 year-old starting pitchers, performing at an average level in the major leagues would be cause for celebration and optimism. Of course, Yankees right-hander Joba Chamberlain isn’t your run-of-the-mill arm.

The 6-2, 230 pounder was taken out of Nebraska with a supplemental first-round pick in the 2006 amateur draft. According to Baseball America (subscription required), Joba didn’t even pitch until his senior year of high school. But in a few short years, he went from a husky hurler getting hammered at Division II Nebraska-Kearney to a slimmed-down star leading the Cornhuskers to the College World Series.

BA’s draft scouting report mentioned that a triceps injury caused Chamberlain to fall down the board a bit, but his stuff was top-shelf. He possessed a “devastating slider,” a low-to-mid-90′s fastball that “should chew up wood bats” and a decent curveball and changeup.

Joba’s pitches did indeed munch on bats in the pros, as he barely spent any time in the minors. In 2007, Chamberlain posted rates of 13.8 K/9 and 2.8 BB/9 with a tiny 2.03 FIP. When hitters weren’t whiffing, they were chopping the ball into the dirt (53.8 GB%).

Earning a big league call-up in August, Chamberlain proceeded to punish hitters out of the bullpen. In 24 frames, he punched out 12.75 batters per nine frames, issuing 2.25 BB/9 with a 2.42 xFIP. Sitting at 97 MPH with his fastball, Joba had a 64.2% contact rate (3rd-lowest among pitchers with 20+ IP) and a massive 35.1 outside swing percentage (25% MLB average).

Since then, there have been endless barstool arguments about Joba’s ultimate role with the Bronx Bombers. In 2008, Chamberlain made 12 starts and 30 relief appearances. He started the year in the ‘pen, transitioned to the rotation in June and then moved back to relief in September following a DL stint for right shoulder tendinitis.

Joba was superb in both roles. To no one’s surprise, he dominated out of the bullpen, with 11.3 K/9, 3.6 BB/9 and a 2.31 ERA in 35 innings. But he was arguably more impressive as a starter, with 10.2 K/9, 3.44 BB/9 and a 2.76 ERA in 65.1 IP. Overall, his groundball rate was a healthy 52 percent.

He didn’t go extremely deep into those games, averaging a little less than 5 and 2/3 innings per start. But the answer to the “starter or reliever?” question appeared to be an easy one. Even the best relievers don’t generally produce the same sort of value as an above-average starter. It’s more difficult to find a quality starter than it is to uncover a ‘pen arm.

In 2009, Chamberlain made 32 appearances (31 starts) in 157.1 innings pitched. The results, while far from bad, were disappointing. Joba’s 4.75 ERA was higher than his 4.56 xFIP, as his batting average on balls in play was a hefty .320. Still, we expected more than league-average pitching.

Chamberlain struck out 7.61 hitters per nine frames, while handing out 4.35 walks per nine innings. He served up 1.2 HR/9, and his home run per fly ball rate wasn’t really the culprit (12.4%, slightly above the average for pitchers). Rather, Joba’s groundball rate fell to 42.9 percent. Some of those extra fly balls cleared the fence at New Yankee Stadium (1.39 HR/9 at home, 0.94 HR/9 on the road). He transitioned to the bullpen for the playoffs.

His plate discipline stats were decidedly average. Joba’s 80.2% contact rate was a tiny bit better than the 80.5% MLB average, and his percentage of contact within the strike zone (90.6) was well above the 87.8% big league average.

His control came and went, with 47 percent of his pitches located within the strike zone (49.3% MLB average) and a 54.7 first-pitch strike percentage (58.2% MLB average). Hitters responded to Chamberlain’s lack of fine touch by chasing few pitches off the plate. Chamberlain’s outside swing percentage was 22.8 percent.

As one would expect, Chamberlain’s velocity dipped as he had to combat lineups several times. He sat between 92 and 93 MPH in 2009, with his high-80′s slider becoming a mid-80′s breaker. Chamberlain also mixed in some high-70′s curveballs and the occasional low-80′s changeup.

Remember that fastball that was supposed to “chew up” lumber? Well, Joba’s heat was one of the least effective pitches in the majors in 2009. He threw the fastball nearly 64 percent of the time, but it had a gruesome run value of -1.26 per 100 pitches thrown. On a per pitch basis, only Jeff Suppan and Carl Pavano fared worse with the fastball.

Joba’s cheddar didn’t show much tailing action. The average right-handed fastball moves in toward a right-handed batter about six inches more a pitch thrown without spin. Chamberlain’s only tailed in toward righties a little more than four inches. Joba’s fastball posted just a 3.3 percent whiff rate. The average for a righty four-seam fastball is about 5.8 percent.

What about that low first pitch strike percentage? According to Joe Lefkowitz’s Pitch F/X Tool, Chamberlain tossed his fastball about 68 percent on the first pitch. He threw a strike with his fastball a meager 52.2 percent of the time in such situations. The average first pitch strike percentage when a righty throws a fastball is about 58 percent.

Chamberlain often ended up at the mercy of his opponents. Hitters worked a three-ball count in 23.4 percent of their plate appearances against Joba, compared to the 20.2 percent average for AL pitchers.

It’s a shame that Chamberlain got behind the hitter so often, as it limited the impact that his breaking pitches could make. His slider (thrown 22 percent of the time) had a run value of +1.29 per 100 pitches, while his curveball (thrown nine percent) was slightly better than average (+0.12). Don’t ask about the changeup (-2.56, though it was tossed just five percent).

With New York’s acquisition of Javier Vazquez, the Yankees have four starting spots set in stone (CC Sabathia, A.J. Burnett and Andy Pettitte are obviously locks as well). That leaves one opening for either Chamberlain or Phil Hughes. Both are well-qualified, and both could certainly end up taking some starts. Clubs just don’t get through a season using only their top five starters.

While Chamberlain didn’t set the world on fire in 2009, he just turned 24 in late September. Hopefully, he gets another crack at the rotation. For the sake of argument, let’s say Joba becomes “only” a 4.00 FIP starter at his peak. If he tosses 175 innings, that would make him worth about 2.7 wins above replacement per season. In 2009, the only reliever to top that WAR total was Jonathan Broxton, with +2.9. It’s awfully hard to make a reasonable argument that Chamberlain has more value out of the ‘pen.

Joba left a sour taste in the mouths of the fantasy owners who dropped a high draft pick on him last year. However, don’t get too discouraged. Surely, Chamberlain has his flaws at the moment. He must do a better job of locating his fastball in order to avoid so many hitter’s counts. That, in turn, would allow him to use his plus slider and solid curve more often. But should we really be shocked that a guy who spent half a season in the minors is rough around the edges?

That’s not to say New York made the wrong decision in bringing him up in 2007-Chamberlain was throttling minor league batters. However, Chamberlain might need some development time before he reaches the lofty expectations bestowed upon him. Pitchers don’t always hit the ground running, progressing in a linear fashion. Joba might not be the instant ace some desired, but there’s plenty of time for him to become a high-caliber big league starter.