Adam Dunn is moving to the American League, signing a four-year deal with the White Sox. More importantly, he's going back to a ballpark that inflates hitters' home run numbers, and he'll be on a team that produces more runs.
Dunn was Mr. Consistent in Cincinnatti, hitting 46 HR in 2004 and then reaching exactly 40 for the next four years (with a short stint in Arizona at the end of 2008). The move to Washington slightly reduced his HR total, as he hit 38 in 2009 and 2010, but now he's going back to a known sluggers' park. ESPN Park Factors shows that US Cellular Field was the best HR park in 2010, whereas Nationals Park was average at 15th. Bill James' Park Index has data specifically for lefties over the last three years, and again Cellular Field ranks high, coming in 7th compared to Nationals Park's 19th. Looking at Dunn in 2011, I'm ready to bank on a HR total back over 40 again, and maybe as high as 45.
There is a downside to leaving Nationals Park, however. Dunn's BA will likely fall back down to his career average of .247. In Bill James' three-year Park Index, Nationals Park ranks higher than Cellular Field in lefty BA and in 2B. ESPN's 2010 Park Factor places Nationals Park higher in hits as well. This data supports the fact that during his two years with the Nats, Dunn saw his best two years in BABIP, a career high in BA in 2009, and a career high in 2B in 2010 (despite a LD% lower than his career mark).
The White Sox (10th in R in 2010) are better offensively than the Nationals (25th), and their ballpark caters to Dunn's power. As such, look for Dunn to have an increase in R, HR, and probably RBI, but don't be surprised to see his BA drop 10 points or more from the last two years (.264 in '09-'10). In rotisserie and H2H leagues the BA might hurt his value a little, but the gains in three categories should offset the loss in one. In points leagues the extra HR, R, and RBI will more than make up for the fewer hits he accumulates.
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