I must admit, the Yankees caught me completely off guard when they signed Chan Ho Park Sunday night. I figured their bullpen was pretty much set with the loser of the fifth-starter battle between Joba Chamberlain and Phil Hughes working the eighth inning, Damaso Marte the lefty, David Robertson as the secondary righty, Alfredo Aceves and Chad Gaudin as long/swing men, and Mark Melancon hoping to make his way into the final spot and force the Yankees to bounce Sergio Mitre from the 40-man roster. So where does Park fit?

Toward the top. Park’s 2009 season doesn’t look that impressive on its face because he was awful in seven starts for the Phillies, but after moving to the bullpen, he posted a 2.52 ERA and struck out 52 men in 50 innings. Over the final three months of the season, that ERA shrank to 1.52. Park wasn’t as sharp in the postseason, but one could blame that on the hamstring pull that cost him a month and kept him out of the NLDS. In his career, Park has posted a 3.95 ERA in relief, nearly a half run better than his career mark as a starter, along with an 8.7 K/9. Indeed, though Park signed so late because he was hoping to catch on elsewhere as a starter, it has been his move to the bullpen over the past two seasons that has salvaged his career in his late 30s (he’ll be 37 in early June).

The first Korean-born major leaguer, Park emerged as the Dodgers’ second-best starter (behind Kevin Brown) around the turn of the millennium and hit the free agent market at the age of 28 with a 80-54 career record and a 3.80 career ERA. The Rangers, who had given Alex Rodriguez the biggest contract in major league history the previous year, signed Park to a five-year deal worth $65 million only to watch him completely fall apart.

The move from the pitcher-friendly Dodger Stadium to the homer-happy Ballpark at Arlington did him no favors , but one could have seen that coming (Park’s home ERA during his Dodger years was 3.19, but his road ERA was 4.72). More alarmingly, after averaging 213 2/3 innings a year in his last five seasons in L.A., Park suddenly couldn’t stay healthy.

A hamstring injury limited Park to 25 starts in 2002, and that was the most he would make in any one season for the Rangers. Meanwhile, while his 6.84 home ERA that season would prove to be sadly typical. Park made just 23 more starts for the Rangers over the next two seasons combined due to a back injury which surely contributed to his 5.96 ERA in those outings. Park’s contract quickly proved to be a major albatross for the Rangers, leading some to speculate that it was part of the team’s motivation for shipping Rodriguez to the Bronx in February 2004.

Park finally stayed healthy in 2005 but was no more effective. When the trading deadline came, the soon-to-be-NL-West-champion Padres, perhaps wagering on the effects of their new pitchers’ haven, Petco, took Park and $13 million of his 2006 salary off the Rangers’ hands for the remains of Phil Nevin. Despite the friendlier home environment, Park’s struggles continued. He posted a 5.91 ERA down the stretch in ’05, and made just 21 starts in ’06, missing time when it was discovered that he suffered from an intestinal defect known as Meckel’s diverticulum. When able to pitch, he posted a 5.45 ERA on the road.

With his contract finally expired, Park didn’t find an employer for 2007 until Valentine’s Day. He signed with the Mets, but failed to make the team out of spring training and wound up making just one appearance for the big club, giving up seven runs in four innings in a late-April spot start before being released. The Astros signed him to a minor-league deal, but declined to call him up as he posted a 6.21 ERA and allowed 18 home runs in 15 starts for Triple-A Round Rock of the Pacific Coast League.

Seemingly out of chances, Park went home again in 2008, catching on with the Dodgers as a non-roster invitee on a minor league deal. Having made just five relief appearances over the previous ten seasons, Park made the Dodgers as a reliever and pitched well out of the pen (3.84 ERA), well enough, at least, for the Phillies, who beat Park’s Dodgers in the NLCS in ’08, to sign him to a $2.5 million deal and bring him in as a fifth-starter candidate the next spring.

As stated above, Park was a disaster as a starter for the Phillies, but he continued to gain momentum as a reliever suggesting that, after six years in the wilderness, he has finally found away to recapture the major league success he had in his twenties, doing so in a hitter-friendly home park, no less.

Despite that success, Park isn’t going to take the eighth-inning job away from the fifth-starter loser, but he could well bounce Robertson down a rung. His presence also all but guarantees that Sergio Mitre will not make the roster, which is worth Park’s $1.2 million salary alone. Park, despite his struggles in the Phillies rotation, also gives the Yankees another potential swing man should Gaudin or Aceves, the former of whom is on a non-guaranteed contract like Mitre and the latter of whom has options remaining, struggle. If Park struggles and Melancon continues to dominate at Triple-A, the $1.2 million the Yankees owe Park is small enough that they could eat the remainder.

Ultimately what Park gives the team is another option, one that had a fair amount of success working out of the pen for playoff teams in each of the last two seasons and thus brings a fair amount of upside to the table, but who also came cheap enough to be discarded if he fails to realize that upside, which means there’s very little downside to the deal. Well done.