The Minnesota Twins have taken plenty of flak for the mass exodus from their bullpen and their many unproven, younger relievers. But the Twins have a much bigger problem on their hands for 2011, one that could threaten their two-year reign as AL Central champs: a severely diminished defense.
The Twins finished sixth in team ultimate zone rating last season. Developed by Mitchel Lichtman and tracked by FanGraphs, UZR is a stat that measures the number of runs a player saves compared to the average player at his position. It’s more reliable on a three-year basis, though, and at times subject to small-sample-size flukes, such as Jason Repko ‘s team-leading performance in just 58 games played.
Random fluctuations aside, the Twins’ biggest defensive downgrade this season comes at shortstop, where Alexi Casilla  takes over for J.J. Hardy . Per UZR, we see that Hardy ranked among the Twins’ best defenders last season. He earned a UZR of 8.1 in 2010, saving just more than eight runs last year as compared to an average defensive shortstop. And this wasn’t a one-year fluke. For his career, Hardy has a UZR of 11.0 per 150 games played. Using the sabermetric convention of 10 runs saved equaling one win gained in the standings, that means Hardy is worth one full win more than an average shortstop each year with his glove alone.
Meanwhile, Casilla is a big unknown as a major league shortstop, having played just 41 games at the position in four-plus years as a mostly part-time player in Minnesota. Without a meaningful sample of games, it’s tough to make an accurate prediction of Casilla’s expected defensive value at short. The scouting reports haven’t been glowing, though, and finding a near-elite defensive shortstop like Hardy is tough to do. And it’s not as if Casilla will be much of an offensive contributor, as his career line is just .249/.306/.395 in more than 1,000 plate appearances.
New Twins second baseman Tsuyoshi Nishioka  comes with a better defensive reputation than Casilla’s. But he, too, replaces a player coming off a strong defensive season for the Twins’ 2010 division-winning squad. Orlando Hudson  saved nearly 10 runs more than an average second baseman last year for Minnesota in just 126 games — down from 2008 and 2009 levels but consistent with longer-term trends and thus likely a pretty accurate reading of his true defensive value to the club. The loss of slick-fielding (though terrible-hitting) utility infielder Nick Punto  compounds the issue.
If the Twins’ defense was stellar everywhere else, you might not worry that much about their middle-infield uncertainty. But Minnesota’s corner-outfield defense ranks among the very worst in baseball. Delmon Young , Jason Kubel  and Michael Cuddyer  cost the team about three wins in their combined time in left and right fields last season, compared to the average player at those positions. That’s consistent with those players’ career track records, which show butcherish tendencies in the field.
Cuddyer was a far worse defender (and a far inferior hitter) than Justin Morneau  when he took over at first base for the concussed slugger this past summer. Morneau has started seeing game action in spring training as he tries to make it back after missing half of last season due to complications stemming from the concussion. If he comes back fully healthy in April, or even May, the Twins could bank a two-way upgrade, with one of Young, Kubel or Cuddyer relegated to DH or the bench when Morneau plays. But Morneau’s health remains a major question mark for the Twins with less than three weeks until Opening Day.
We’re still learning about the connection between pitching and defense and exactly how much catching the ball means to a team’s run prevention. Although stats such as UZR and defensive runs saved above average do a pretty good job of quantifying defensive impact, one factor which can get lost in the calculus is something we can call “cascading.”
Here’s an example of how cascading can play out: bases loaded, one out, pitcher induces a grounder up the middle. A good shortstop fields the ball, tosses to second for one, on to first, inning-ending double play, crisis averted. A lesser shortstop lets the ball go through. But it’s not just the two runs that score that hurt the team on the field; it’s also the added strain it places on the pitching staff. The pitcher on the mound still needs two more outs to escape this high-stress situation. If he can’t get out of the jam, the manager will have to make a call to the bullpen earlier than he’d like. Now you’re getting your lesser middle relievers into the game instead of your better late-inning guys, meaning you’re liable to give up more runs. You’re also forcing the bullpen to generally work harder, raising the risk that your relievers could wear down as the season goes on, if your defense continues to struggle. The end result can be more runs allowed, more fatigue for your pitchers and even a greater risk of injuries.
In the Twins’ case, more grounders could shoot through holes with Hardy and Hudson gone, and line drives and deep flies could land in the gaps, given the team’s weak corner-outfield defense. This is important because Twins have a pitch-to-contact staff that finished 10th in the AL in strikeouts in 2010. Minnesota’s pitchers need a good defense to thrive. So whether you’re a ground-ball-oriented pitcher like Francisco Liriano , Carl Pavano , Nick Blackburn  or Brian Duensing , or an extreme fly-ball pitcher like Scott Baker  or Kevin Slowey , you’re vulnerable to the team’s defensive problems.
Losing four established relief pitchers from last year’s squad could dent the Twins’ chances, although the return of Joe Nathan  and a full season of Matt Capps  should help. The White Sox should be better than they were last season, although they still have question marks at multiple positions. But if Minnesota fails to three-peat in 2011, that leaky defense could be the biggest reason.