Posted by David Golebiewski on Saturday, March 13, 2010 at 4:17 pm

According to the Associated Press, Denard Span has inked a five-year, $16.5 million contract extension with the Minnesota Twins. Span, 26, wasn’t eligible for salary arbitration for another two seasons, so the deal takes him through his arbitration years. There’s also a $9 million club option for the 2015 season, Span’s first year of free agent eligibility.

Twins GM Bill Smith told the AP:

We’ve seen [Span] grow from the rookie league, step by step through the minor leagues and he’s in the process of fulfilling all of those expectations, all of those projections that our scouts made on him when he was in high school.

Indeed, Span has progressively improved his game over the years. The 2002 first-round pick posted a cumulative .287/.357/.358 line in the minor leagues, walking in 8.8 percent of his plate appearances and striking out 17 percent. The 6-0, 205 pound lefty batter showed precious little pop, with a .071 Isolated Power.

Back in 2005, Baseball America described Span as a “potential game-changer on the bases,” with wheels that “enabl[e] him to outrun mistakes.” Despite that praise, the Florida prep product swiped bases as a paltry 66.1 percent clip. Span’s defense rated pretty well according to Sean Smith’s Total Zone, but BA mentioned in 2006 that “he sometimes has to rely on his quickness to make up for mistakes on routes in center field.”

He certainly didn’t lack talent, but there was a feeling that Span just wasn’t getting the most out of his skill-set. “Tools aren’t Span’s problem,” Baseball America quipped in 2007. “Putting those tools to use are.”

Since making his big league debut in 2008, Span has learned how to use those tools , hammering away at that underachiever label (he credits LASIK surgery, which improved his eyesight). In 1,087 plate appearances over the past two seasons, Span has hit .305/.390/.422 while showing unprecedented secondary skills. He has drawn ball four 11 percent of the time, posting a .117 ISO. It’s not like Span has emerged as a hulking slugger, but he has assuaged concerns that he’d get the bat knocked out of his hands at the highest level.

Span’s plate discipline has been superb. When an opposing pitcher tosses a junk ball off the plate, Span rarely indulges: his outside swing rate in the majors is 17.7 percent, compared to the 25 percent major league average. Over the last two seasons, Span has gone fishing out of the zone at the ninth-lowest rate among all hitters.

He rarely whiffs, either. Span has a 16.1 percent strikeout rate, with an 89.4 percent contact rate (80-81 percent MLB average). That’s the seventh-highest rate among big league batters over the 2008-2009 seasons.

Span has handled fastballs with aplomb (+0.72 runs above average per 100 seen), a good thing considering pitchers have brought the heat nearly 67 percent of the time against him (the fourth-highest rate in the majors since 2008). But he does serious damage when a hurler throws something that bends: he has a +2.64 run/100 pitch value against sliders, and a +2.53 mark versus curveballs (the second and ninth-best best rates in the bigs, respectively).

On the base paths, Span has also shown some improvement. He has nabbed 41 bases in 58 attempts, a 70.7 percent success rate. That’s still not especially good: according to Baseball Prospectus’ Equivalent Stolen Base Runs metric, Span has actually cost the Twinkies about 2.3 runs with his base stealing over the past two years. However, he’s adept at other aspects of base running, such as taking the extra bag on hits and advancing on wild pitches and passed balls. In terms of overall Equivalent Base Runs, Span rated as +3.3 runs in 2008 and +1.6 in 2009.

Defensively, the long-time center fielder has split his time between the outfield corners and the middle garden. In the corners, Span has a +9.3 UZR/150 in 1,366.2 innings. In center, he has a -13.8 UZR/150 in 704 innings.

Given the sample size, it’s best not to make too much out of Span’s poor rating in center. Historically, the difference between a corner outfielder and a center fielder has been about 10 runs. In other words, corner outfielders playing center field have been about 10 runs worse per season in center than in the corners, while center fielders manning the corners have been about 10 runs better in the corners than in center field. Span figures to be about an average center fielder. Sean Smith’s Total Zone has Span as a +2.9 run defender in center next year.

Add up Span’s keen eye, contact ability, adequate power, base running advancement and solid D, and you have a three-plus win player now signed through his peak years. According to MLB.com’s Kelly Thesier, Span will make $750,000 in 2010, $1 million in 2011, $3 million in 2012, $4.75 million in 2013 and $6.5 million in 2014 (there’s a $500,000 buyout if the 2015 option isn’t picked up).

How good of a deal is this for the Twins? Let’s evaluate the three arbitration years specifically. For the sake of argument, say Span is a three-win player in 2012 and 2013 and declines to 2.5 WAR in 2014 (just rough estimates, taking into account some decline). Based on the MLB salary arbitration study I did last week, Span would be expected to earn 29 percent of his free agent value during his first year of arbitration, 49 percent during the second year of arbitration and 68 percent in his final year prior to free agency.

It’s hard to estimate baseball’s economic climate several years down the road, but let’s say that one WAR will cost $4.6M in 2012, $4.8M in 2013 and $5M in 2014. Using those assumptions, here’s how much Span’s production would be worth on the free agent market, how much he would be expected to earn via salary arbitration (using the 29 percent first-year/49 percent second-year/68 percent third-year free agent value figures), and how much Span will actually be paid during those seasons:

It’s not a staggering amount for the Twins, but more than $5 million saved compared to what Span would have likely gotten through salary arbitration is nothing to sneeze at. This looks like a winner for both sides: Minnesota locks up a quietly productive player at a discount, and Span gets to play ball knowing that he’s financially set for the rest of his life.