The Yankees have signed their first Type A free agent of the offseason, re-upping lefty reliever Damaso Marte, whose $6 million option they had declined just last week, with a three-year deal worth $12 million with a club option for 2012. Marte joined the Yankees just before the trading deadline this year in the deal that also brought Xavier Nady over from the Pirates.

Marte’s Yankee career didn’t get off to the best start as he struggled in two of his first five outings for the Bombers, allowing six runs in his first 4 2/3 innings. His fifth Yankee appearance saw him throw 42 pitches in 101-degree heat in Texas. Marte hadn’t thrown that many pitches in a single outing since August 2006 and promptly developed discomfort in his pitching elbow. Four outings later, Marte turned in another stinker, setting his Yankee ERA at 11.05 after nine appearances. Though Joe Girardi insisted that there was nothing wrong with the Dominican lefty, Marte faced just one batter over the next nine days, eventually informing the media of his elbow discomfort on his own.

The time off did trick as Marte returned to action on August 22 and posted a 1.64 ERA over his last 15 appearances, striking out 13 in 11 innings, while allowing just nine baserunners. The Yankees have clearly chosen to focus on those last 15 outings rather than on the first nine and that bit of elbow pain.

By declining Marte’s option only to resign him to a multi-year deal, the Yankees have done exactly what many expected they would, though I’m troubled by the length of the deal, particularly given that Marte will turn 34 before pitchers and catchers report. Perhaps the most significant success of the 2008 Yankees was their ability to piece together one of the best bullpens in baseball from an assemblage of home-grown arms and minor league free agents. Perhaps just as impressively, they were able to replace parts on the fly when, for example, Brian Bruney broke his foot, or Joba Chamberlain moved into the rotation.

That success seemed to teach the Yankees all they needed to know about the fungibility of relief pitchers, prompting them to release struggling veteran LaTroy Hawkins, whose signing last winter seemed like little more than a hedge against betting the pen on those other unproven arms, and trade Kyle Farnsworth, the lone big-money holdover from past failed attempts to buy a better bullpen, in the wake of the acquisition of Marte. When Marte struggled in his first month as a Yankee without doing much damage to the pen as a whole, that seemed to provide another lesson. Still, here we are again, evaluating a three-year deal for a veteran set-up reliever.

I would have understood if the Yankees had picked up Marte’s option, using him as a hedge against coming set-up man Mark Melancon or against a second look at lefty Phil Coke in the major league pen. I would have understood a two year deal at a reduced salary, which would have allowed the team to trade Marte either at the deadline or next winter. Three years plus an option? That I don’t get. Not when the option would be for Marte’s age-37 season. Not given that bit of elbow trouble in August. Not given all of the pitching already in the Yankee system.

Still, here he is. So who is he?

Marte was originally signed by the Seattle Mariners as an international free agent out of the Dominican Republic. He worked his way up through the Mariners system as a starting pitcher, eventually making his big league debut with five shaky relief outings in mid 1999, but wasn’t particularly effective at any level along the way. He then lost most of the 2000 season to injury and signed with the Yankees as a minor league free agent almost exactly eight years ago. Pitching exclusively in relief for double-A Norwich, Marte was outstanding for the Yankees, who cashed him in by flipping him to the Pirates in mid-June 2001 for infielder Enrique Wilson. Wilson hit .216/.261/.332 across parts of four seasons for the Yankees, making Miguel Cairo a legitimate upgrade. Marte, meanwhile, established himself as a major leaguer in the Pittsburgh pen, then was flipped again at the end of spring training, this time to the White Sox for minor league righty Matt Guerrier, who has since established himself in the Twins bullpen.

It was with Chicago that Marte, by then 27, established himself as one of the best set-up men in baseball. As a LOOGY in 2002, Marte held lefties to a .149/.237/.218 line, struck out 72 men against 18 walks in 60 1/3 innings, and finished eighth in the AL with 3.42 WXRL. He actually finished that season as the Chisox’s closer, going a perfect 8 for 8 in save opportunities while striking out 30 against four walks in 21 innings and posting a 1.29 ERA after July 27. The next year, he maintained that expanded role, though he shared closing duty with Tom Gordon and Billy Koch and was just 11 for 18 in save opportunities. Still, he posted a stellar 1.58 ERA, struck out 87 in 78 2/3 innings and finished ninth in the majors with a 4.42 WXRL.

Marte was less effective in 2004, and was back in the LOOGY role in the White Sox Championship season in 2005, which was otherwise Marte’s worst major league campaign. A rising walk rate sabotaged his effectiveness in 2005, as lefties reached base at a .389 clip against him that season. That December he was traded back to the Pirates for utility man Rob Mackoviak. Marte remained a LOOGY in his first two years back in Pittsburgh, but had returned to more of a general set-up role last year prior to being acquired by the Yankees.

A hard-throwing lefty with a put-away slider, Marte is a strikeout pitcher with occasionally troubling walk rates. He has had reverse splits the last two years and hasn’t dominated lefties since 2004, but he strikes out more than a man per inning and does a good job of keeping the ball in the park. For that reason, he’s best used as a full-inning set-up man. As long as his elbow stays healthy and Joe Girardi avoids using him as a match-up lefty, he should be an asset to the Yankee pen, though he may ultimately be most valuable as a trade chip once some of the coming young arms in the system establish themselves in the major leagues.