Matt Kemp isn’t just in need of an offensive improvement in 2011. As Jerry Crasnick alluded to in his piece on Tuesday, Kemp is in need of an upgrade on the defensive side, as well.

KempKemp’s defensive numbers slipped as much as his offensive ones did in 2010. Baseball Info Solutions (BIS), which charts every batted ball in the major leagues based on how frequently it was turned into an out, rated Kemp 35th in its plus/minus among the 35 center fielders who played the most innings last season.

Kemp finished at minus-12. That means he made 12 fewer plays on batted balls than the average center fielder (leading to 23 total bases for opposing hitters).

That’s just part of a two-year decline for Kemp, who ranked 17th in that stat in 2008 and 28th in 2009.

Kemp had been able to offset this deficiency by keeping runners from taking extra bases, either with a quick recovery or a strong arm. That may have played a role in his winning a Gold Glove in 2009.

Last season, however, Kemp’s presence was a non-factor (see chart). Opponents were able to run on him as needed.

Baserunners vs. Matt Kemp
Past 2 Seasons

BIS has a formula that can convert those numbers into runs saved (the defensive statistical equivalent of Bill James' runs created measurement). In 2009, Kemp saved nine runs with his arm, second best among center fielders. In 2010, Kemp’s arm cost his team two runs, dropping him to 28th in the rankings.

Additionally, Baseball Info Solutions has video scouts chart every play into more than 80 categories (30-plus of "Good Fielding Plays", 50-plus categories of "Defensive Misplays").

Good Fielding Plays would be those that you would typically consider a "Web Gem Nominee" on "SportsCenter" or "Baseball Tonight." Defensive Misplays include slipping, overthrowing a cutoff man, having a ball bounce off the wall and roll past an outfielder and other issues.

Kemp finished last season with 27 Good Fielding Plays and 33 Defensive Misplays and Errors. His minus-6 "net rating" tied for eighth worst out of 106 players who appeared in center field last season. Kemp’s biggest issues were dealing with outfield fences (he had six "wall misplays," tied for second most in the majors) and failing to hang on to the ball once he got a glove on it (which happened five times in 2010).

So although a return to form on the offensive side by Kemp is what many will be watching for this spring, it would be worthwhile to keep an eye on his defensive performance, as well.