Jacoby Ellsbury will find the middle ground
In 2011, the Red Sox' center fielder was arguably the best everyday player in the American League, hitting 32 home runs with 39 stolen bases and a .928 OPS in a career-high 158 games. However, in the two seasons (2010, '12) surrounding what right now looks like a career outlier, he played a total of 92 games and hit four homers combined, the seasons essentially lost because of significant impact injuries that resulted in broken ribs and a separated shoulder.
It's not a news flash that Ellsbury is in the final year of his contract, and provided he can avoid fluke injuries, the belief here is that he'll be similar to the player he was in 2009, when he hit .301 with 8 homers and 70 steals in 153 games. Give him about 10 more homers and knock off 20 steals from his '09 totals, and that seems a reasonable expectation for what he is capable of this season.