It appears Luis Castillo will be the Mets' primary second baseman in 2010, despite reported attempts by the front office to trade him this offseason. Moving Castillo for basically anything (except Gary Matthews Jr.) and targeting Felipe Lopez or Adam Kennedy was/is the smart play, but there haven't been any recent trade rumblings or free agency rumors. So here we are with our man Luis. The elephant in the room is his glove. After several years of decline, his defense seems prepared to fall off the Cliffs Of Moher. Observe three of our favorite defensive statistics' evaluations of the $25 million man:

One year of defensive stats can often be written off as noise. Three consecutive years of poor play is hard to ignore. The Fan's Scouting Report also delivers some unimpressive marks and I think most Met fans would agree that his defense was lacking. Optimistically, Castillo's SB Nation profile blurbs the following:

Assets: Has good speed and quick feet, which helps to give him range on defense

The first part of that scouting report is reasonable, given his stolen base and baserunning numbers. Respect to SBN, but calling his range an asset is a colossal stretch. What are the chances that Castillo is anything less than disastrous in the field? Slim, likely, but the following factors might make you say "So you're telling me there's a chance?".

Conditioning

Derek Jeter experienced something of a defensive rejuvenation the last couple seasons. After many years of pitiful play, in which he deservingly earned the nickname "past-a-diving", he improved in 2008 and was more than adequate in 2009. Statistics, scouts, fawning members of the mainstream media -- all generally agreed on the improvement. As Bryan Hoch noted, 35 year-old Jeter spent the last two seasons working on his athleticism and mobility. One wonders why it took so long to work on an obviously lacking aspect of his game, but the takeaway is that 34 year-old Castillo might not be a totally lost cause. Of course, he entered last spring training in-the-best-shape-of-his life. This lead to his finest offensive season in four years, but an awful defensive one. A 2010 with Castillo in anything but the best shape could be catastrophic. Maybe the Mets need to bring in a conditioning coach who specializes in helping players improve their lateral movement. I have no suggestions for such a coach but apparently the Yankees employed one with Jeter.

Positioning

This is an often overlooked facet of defense. I hate to bring up Jeter again but "aggressive defensive positioning" by Yankees infield coach Mick Kelleher was listed as another reason for the shortstop's improvement. John Dewan, proprietor of the Plus/Minus system, wrote the following at The Hardball Times on employing defensive shifts:

Aside from the three fielders at third base (who combine for a +51 plus/minus), we observe a general trend: the group of infielders with the largest LHB/RHB differences had a higher plus/minus score than the group that shifted the least.

Click through to read the entire article, but basically his data seems to suggest that infielders (especially 2nd basemen) who shift dramatically performed better defensively. I didn't chart Castillo defensively this season, nor am I a scout qualified to accurately assess defensive performances. However, take a look at how he has performed on batted balls to his left and right, according to Plus/Minus:

That's +22 to his right and -39 to his left, for those who can't read spray-can. Granted much of that positive to-his-right was years ago, but he still appears to be shakier when going to his left. Perhaps some "drastic shifting", to quote Dewan, is in order. Something -- anything -- to save Castillo's defense and the ERA of the Mets pitching staff.

Recent injuries, age and having one leg longer than the other are hindrances to a Castillo defensive renaissance. There's optimism and there's being realistic. A conservative defensive projection is something like -6. Given this, a ~1.7 WAR season looks like Castillo's ceiling, with reality about a half win lower. Improved positioning, based on analysis of Castillo's weaknesses, scouting reports of hitters and the general "expertise" of the coaching staff, is what we can hope for.