Entering 2011, Jacoby Ellsbury had hit 20 home runs in 1,372 career major league at-bats. He'd missed nearly all of 2010 with a rib injury. The Red Sox had signed Carl Crawford to provide some dynamic speed for the top of the Boston order, presumably moving Ellsbury down to the bottom of the lineup.
Ellsbury did begin the season in the leadoff spot, but after hitting .167 through six games was moved down to the No. 8 hole; and then he was moved down to the No. 9 hole. Through April 21 he was hitting .186, although he had hit four home runs.
Terry Francona then moved him back to the leadoff spot and Ellsbury started to hit. Sort of. He actually started 33 games in a row in April and May without hitting a home run, but had raised his average to .295 through May 25. From May 26 to the end of the season he hit a robust .332/.383/.600, with 28 home runs in 467 at-bats and finished second in the AL MVP vote.
Was the power outburst for real? The impressive thing about his 32 home runs is he did it without sacrificing other elements of his game -- he still hit a career-high .321 and his strikeout percentage was only 1.6 percent higher than his previous career rate. His home run/fly ball rate wasn't necessarily extraordinary -- 16.7 percent, which ranked 29th among MLB regulars.
How much luck was involved in his 32 home runs? The ESPN Home Run Tracker breaks down home runs into different categories, including "just enough" (barely cleared the fence) and "lucky home runs" (a home run that would not have cleared the fence on a calm, 70-degree day). Miguel Cabrera led the majors with 16 "just enough" home runs. Ellsbury had just four such home runs. He had three "lucky" home runs. In other words, the power -- at least in 2011 -- was legitimate.
There still seems a lot of doubt in Ellsbury's ability to do it again, however. The projection systems aren't kind, settling around 20 home runs or so. I'm a little more optimistic and will set the over/under at 24.5 home runs.