I find the number a little surprising. Ells got $8.05 million last year after his near-MVP performance in 2011. And sure, players don't often go backwards in arbitration, but it's surprising to see the number jump up another million when he played half the year, and when he played he was pretty average. A .313 OBP for a leadoff hitter ain't great; four homers speak for themselves.
I know the Red Sox prefer not to go to arbitration, but were I in Ben Cherington's shoes, I might have done it. If you're an arbitrator, what track record are you more convinced by, the one massive breakout year, or the two injury-riddled ones surrounding it? It makes me think that the Red Sox consider an extra million or two worth spending to A) avoid dealing with the hassle of arbitration and B) keep the lines of communication strong with Scott Boras. Maybe they'll be in on the Ellsbury sweepstakes next year after all?