Since the news has come out that Alfonso Soriano will undergo season-ending knee surgery today, I figured this would be as good a time as any to do a quick overview of his disastrous 2009 season.

Alfonso Soriano

#12 / Left Field / Chicago Cubs

Height: 6-1

Weight: 180

Bats: R

Throws: R

Born: Jan 07, 1978

Soriano's 2009 season has been a horror anyway you slice it, and it's about to get a whole lot worse from here. There is a great deal of distress in Cubs nation regarding Soriano, especially as he is about to be paid $18M annually for the next five seasons. But I'm not here to talk about the ridiculousness of that deal; instead, I'll talk a little bit about the ridiculousness of Soriano's year.

Soriano has put up some ghastly numbers at the plate and in left field this season. That .241/.303/.423 line was good for a .314 wOBA, 8.8 park-adjusted runs below league average according to FanGraphs. UZR did not like his glovework out there either, logging him at 11.5 runs below average in about 1000 innings this season in left field. Overall, Soriano and his $16M salary have produced -0.8 WAR, costing the Chicago Cubs $3.7M over some Triple-A scrub corner outfielder.

However, and this is either good or bad for Cubs fans, Soriano has looked mostly the same at the plate this season as he has been the last few years.

He's the same man you signed.

Last year, Soriano posted a nifty .374 wOBA, batting .280/.344/.532. He also stole 19 bags while being caught only three times, more than worth his effort. In total, he was worth 16.4 park-adjusted runs above your average major league hitter, which is light years away (OK, only 25.2 runs away) from his production this year. But what's changed? Not much.

(Note: This is my first attempt at anything more complicated than a straight bar graph. I've had no practice at such things, so if this ends up being terrible, I apologize.)

For Soriano, all of the more stable statistics such as swing, contact, strikeout, and walk rates have remained the same. This season Soriano converted five percent of line drives from the previous year into ground balls, which more or less explains the difference between his batted ball types this year. These numbers have actually remained stable not just from last year to this year, but from all the way back to his only season with the Washington Nationals. Soriano has more or less had the same hitting profile that he's had since coming over to the National League from the Texas Rangers in 2006.

There is, of course, one exception, that being the large decrease in ISO this year, and that exception has been the downfall of Soriano's production. I adjusted ISO so that it would weight doubles and triples equally (as triples are usually more dependent on speed and ballpark factors than power), but it surprisingly did not matter much, as Soriano has only one triple in the last two years. This season's ISO is a drastic drop from the trend he set in the last few years. Here's where his power is dropping.

You can see that the biggest indicator of power loss for Soriano is his drop in HR/FB%. We all know that normally fluctuates around a mean, so some of his slumping may be bad luck. But his lack of power may also something to do with the very factor that's ending his season today.

Knee's the Word

Soriano's knee issues aren't necessarily recent; apparently Soriano has had the nagging injury since an April 22 collision with a wall. He's mostly been playing through the pain this season. The location of the injury, his knee, suggests that his range in the outfield has been negatively affected. His range since playing full time in the outfield has dropped from 4.5 his initial season with Chicago to -1.1 last year to a career low -5.0 runs this season. However, his arm runs have also decreased and he's committed more errors this season, so range as a result of his knee may not be the only factor.

Given that the rest of Soriano's hitting has been the same, perhaps his knee can be attributed to his power loss. But Hit Tracker has his home runs actually traveling farther this year than last year on average, so perhaps the injury isn't affecting him as much as Cubs fans would like to think it is. Either way, Soriano's approach this season has been essentially the same as the three years before, when he posted .370+ wOBA seasons. Like it or not, the Cubs will be paying for mostly the same guy they signed in 2007. His game is predicated on his power, because he isn't going to get on base at a high clip, so for the Chicago Cubs to get even close to their $18M investment for the next few years, it is imperative that Soriano recover from this knee injury and get back to roaming the outfield and putting the ball in the stands.