The Arizona Diamondbacks signed outfielder Jason Kubel to a two-year, $15 million deal on Monday to become the club's starting left fielder. The move might provide the D-Backs with a moderate offensive upgrade over incumbent Gerardo Parra, but it's a net loss overall that makes Arizona older and defensively-challenged at the position-- a particularly bad scenario given the fly ball-slanted nature of most of the team's starting pitchers.
Kubel, 29, is coming off a season in which he hit .273/.332/.434 and had a 111 OPS+ in 401 plate appearances, missing the better part of two months with a sprained left foot. Parra, meanwhile, batted .292/.357/.427 last year, with a 113 OPS+ in 493 plate appearances. Granted, Parra wasn't nearly as effective in 2009-2010 (84 OPS+ in 884 plate appearances), and his improved walk rate last season was largely the result of 16 intentionals because he often batted in front of the pitcher.
Moving forward, Kubel probably has the offensive advantage over the 25-year-old Parra. Bill James projects a .274/.343/.466 line for Kubel in 2012, compared to .293/.352/.427 for Parra. Over the course of a full season, Kubel is about 10 runs (or one win) better with the bat if you go by Bill James. But the equation isn't that simple. Parra is a plus fielder, Kubel is a born DH, and Arizona's staff takes to the air more than most.
Over the course of his three-year career, Parra has saved about 11 runs more than the average left fielder per 150 defensive games, according to Ultimate Zone Rating. The 220-pound Kubel, who has a blown knee in his past in addition to the foot issue, has been 17 runs below average per 150 games in an outfield corner. Even if you think Parra isn't quite that swift afield and that Kubel isn't that much of a plodder, the defensive difference wipes away any advantage Kubel holds over Parra at the plate.
Compounding matters, several of Arizona's starters give up a lot of fly balls. That's not the case for newly-acquired Trevor Cahill (29% fly ball rate last year), but Ian Kennedy (42 FB%), Dan Hudson (41%) and especially Josh Collmenter (50%) allow hitters to loft the ball more than the average starter (35-36% fly ball rate in 2011). Barry Enright, who projects as the team's 5th or 6th starter to begin the year, also gave up fly balls 44% of the time batters put the ball in play.
Overall, this move looks like a waste of resources for the Diamondbacks. Kubel may well provide an offensive upgrade, but he gives that back and perhaps then some when you consider that Parra is an elite corner outfielder and Kubel covers ground like someone replaced his cleats with cement blocks. The better course of action would have been to bring in a much cheaper right-handed hitter -- say, Andruw Jones -- to spot for Parra against tough left-handed pitching. Instead, Kennedy, Hudson and Collmenter will cringe every time a fly ball heads Kubel's way.