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 Mitchel Lichtman's Ultimate Zone Rating (which is based on Stats Inc.'s Zone Rating and applies a run value to a player's defensive performance) or Baseball Information Solutions' Plus/Minus (system that mixes batted-ball data and systematic observation to evaluate defensive performance), the statistical measures of defense do a better job of telling us what a player did with the chances he had to make plays, whether those balls became hits or errors, whether he made a play because he's fast, possesses a gun for an arm or gauges hitters well and slides that extra step before the ball is hit.
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 Torii Hunter to right field is one backed by advanced metrics. By UZR, Hunter hasn't been saving runs relative to an average center fielder since 2005, and at -3.7 he was headed to his third-worst defensive season ever when the move was made last week. He is +1, which is a bit better, but still puts him on the way to his second below-average year in the last three. None of this is surprising; Hunter turned 35 last month, and center field is a young man's game. The statistics lay out what something like Gold Glove voting -- driven by highlight reels and reputation -- doesn't: Hunter isn't converting balls into outs as well as he used to, and that's the only thing that matters.
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 Peter Bourjos forced the issue, and the Angels' fade to third place in the AL West may have made it easier for the team to make the switch.
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.
Yuniesky Betancourt, "SS", RoyalsUZR: -6; Plus/Minus (2008-2010): -30
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.
Brad Hawpe, "RF", Rockies2010 UZR: -4.4; Plus/Minus (2008-10): -39
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 Jim Tracy to find more playing time this season for Seth Smith and Ryan Spilborghs. Hawpe's poor defense may be one reason the Rockies haven't been able to deal him to clear their logjam; other teams, with access to the same information, may see him as a first baseman or DH rather than an outfielder. The Rockies will have a tough call on whether to pick up his $10 million option after the season; Hawpe's left-handed power seems worth the money to some teams, but the risk is that they will continue having trouble trying to deal him.
Hanley Ramirez, "SS", Marlins2010 UZR: -8.4; Plus/Minus (2008-10): -2
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.
Andre Ethier, "RF", Dodgers2010 UZR: -16.3; Plus/Minus (2008-10): -22
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 James Loney means the Dodgers can't move Ethier to first base but perhaps more time in left field -- the easier field in most parks -- would limit the damage he can do.
Ryan Braun, "LF", Brewers2010 UZR: -10.2; Plus/Minus (2008-10): -12
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 Prince Fielder, they can consider that moving Braun to first base is rapidly becoming a necessity.
Want a positive precedent? Adam Dunn was one of the worst defensive players in baseball from 2006 through 2008. The Nationals converted him to first base, and Dunn has adapted well, showing good hands if limited range. It's rare that a player can move to first base and increase his value, but Dunn has done so. Braun, who isn't quite as bad as Dunn was in left, could do the same.
Honorable mention goes to two aging corner outfielders, Carlos Lee of the Astros and Bobby Abreu of the Angels. Both were adequate defenders when younger -- Abreu was actually very good when he came to the majors -- but both are now liabilities in the field. In both cases, the problem is that neither is hitting enough to move to DH or first base. It is at this point that careers come to a crashing halt. Lee is going to get paid through 2012 one way or another, but he may be cashing those checks from home. Teams are no longer going to let aging sluggers kill them on both sides of the ball. Abreu could well have a hard time finding a suitor this winter, given the falloff in his production and the need to consider him a DH.
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 Julio Lugo rated terribly at shortstop, and now doesn't get to play there -- or anywhere -- much, with his third team in two seasons. Gary Matthews Jr. lost his bench value, and soon after his roster spot with the Mets when he became unable to cover center field. No one considered Miguel Tejada a shortstop last offseason in part because of his brutal stats (including a -12.4 UZR) at the position in 2009, and he moved to third base with the Orioles this season (he's now back at SS now following a trade to the Padres). Jermaine Dye couldn't find a job this year because no one wanted to let him play right field -- his UZR of -21.6 in 2009 made him the worst defensive player in baseball last year.
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.