Advances in both the quantity and caliber of data collected have changed the evaluation of defensive performance. For more than a century, fielders were judged based primarily through observation and error counts, neither of which corresponds particularly well to the job of preventing runs. Defensive skills -- speed, hands, arm, footwork, positioning -- are just loosely correlated to defensive performance. Errors are actively misleading; players who collect few errors often do so by not getting to very many balls, transferring the demerit -- a hit -- to their pitcher and getting off scot-free.
Now, we evaluate fielders the same way we evaluate hitters: performance in the context of opportunity. Whether
Defensive statistics aren't perfect; we don't necessarily have the same level of confidence in a UZR of -13.5 or a +/- of -6 that we do in a triple-slash offensive line like .234/.288/.340. I know the latter player is hurting his team at the plate; I can't make quite as strong a statement off of one piece of defensive data. So in evaluating defense, you want to look at multiple systems and multiple seasons, to increase your confidence in the information and make sure you have enough to act upon. And while the revolution in offensive stats has been leveraged by fans in managing their fantasy baseball teams, measuring defense is something that only teams can put into action.
Yes, action. It's one thing to have these tools, but they're only useful if teams use them to make decisions about the use of their personnel. The Angels may not be an organization known for using stats, but the move of
If there's an unusual element to this decision it's the Angels' choice to make the move in-season. Switching positions, even from one outfield slot to another, isn't an easy thing to do on the fly. Hunter hadn't played anywhere but center since 2000. The presence of speedy prospect
There are other players who, like Hunter, are hurting their teams so much in the field that a position change, or perhaps a benching, is long overdue. In identifying these players, I looked at both UZR and +/-, and at data going back to 2008, to ensure that these players weren't being misidentified off of insufficient information. These are all among the worst defensive players in the game.
Betancourt is the worst defensive shortstop, and probably the worst defensive infielder, in baseball. He's cost his teams a consistent 10 to 20 runs a year with poor range and mistake-prone play. It's possible that a move to second base would correct one of these issues, but the question is, "why?" Betancourt's terrible bat -- he's posted sub-.300 OBPs the past two years -- invites the question of why a team would keep a player who's bringing so little to the table on its roster. He brought a strong defensive reputation with from Cuba but it hasn't translated stateside, and it's time to see him for what he is: a liability. The Royals absolutely have to put a strong defense on the field as they develop homegrown starting pitching over the next couple of seasons, and Betancourt can't contribute to that. He should be released; not converted to second base or utility infielder, but released.
Hawpe slugged .498 or better in four straight seasons starting in 2006, yet has found his playing time slashed in 2010. The Rockies' outfield depth is part of the reason, but the converted first baseman's poor range in right isn't helping. Hawpe was the worst defender in baseball in 2008 and the second-worst in 2009 by UZR, making it easy for Colorado manager
The best player on our list, Ramirez was considered to be on his way to center field during his first two seasons in the majors, and a comically poor -20.5 UZR in 2007 seemed to seal the deal. The Marlins never moved him, however, but after two years of average play at short, Ramirez is once again costing them runs, on his way to being a -10, -12 defender this season. At 6'3", 230 pounds, Ramirez is big for the position and may simply be outgrowing shortstop. He's already lost some of the speed he came into the league with -- he has 22 stolen bases this year compared to his career highs of 51 in 2006 and 2007. Given his importance to the franchise, it may be time for the Marlins to slide Ramirez to third base or left field in an attempt to improve their defense at multiple positions, while giving their best player a chance to become a defensive asset.
If there's one clear surprise in the numbers, it's that Ethier is among the worst outfielders in baseball for the second straight year, as measured by both systems. Ethier has gotten consistently, progressively worse since his rookie season, and is approaching Hawpe-like numbers in the field in 2010. Ethier doesn't look like he would be a bad defender, but the consistency of the measurements serve as a lesson: defense cannot be measured by observation, no more than you would look at a batter all year and determine whether he was good or not from your memory of his at-bats. The presence of
Braun is in the midst of flunking a second position, having put up one of the worst defensive performances on record as a rookie third baseman in 2007, when he posted a -27.7 UZR. He was so bad that the Brewers had no choice but to send him to left field, and while he's been a better left fielder than a third baseman, he hasn't been good. Braun cost the Brewers about one win (10 runs saved equals one win; 10 runs allowed equals one loss) last year and is headed for the same performance this year. Mind you, these are the years in which Braun should be the most agile. It's hard to see how he'll get better with age. If the Brewers need another incentive to trade
Want a positive precedent?
Honorable mention goes to two aging corner outfielders,
We expect players to lose their jobs because they don't hit. What's interesting is how many players do lose jobs because they cannot field. Baltimore's
Teams don't have to guess any longer. Not only can we measure defensive performance, but we can quantify it relative to offense. The best defenders in most years are worth 20-25 runs above average, and the worst, 15-20 below. Those numbers are getting factored in just as much as VORP or EqA, allowing teams to get a fuller picture of what a player brings to or takes off the table. There's no longer hiding behind high fielding percentages or blinding athleticism. There's just your numbers.