Because of Scott Boras, I don't see Ellsbury returning to Boston after this season. Boras rarely changes his mode of opperation even after players like Michael Bourne and Kyle Lohse suffer from his strategies. Ellsbury will test the market unless he is injured again and needs to re-sign a one year contract to re-establish his value.
That said, the Sox are in a hard place with Ellsbury. His trade value is hurt by Boras and the injuries. Actually, Ellsbury is also hurt by Boras and the injuries. He would be better off dumping Boras and re-signing with the Red Sox. As someone else said, his market will likely be limited to Seattle where he will likely be the next Chone Figgins.
As for Bradley, the Sox would be fools to bring him north off a hot spring training. Spring training is too a small sample size to get excited over. He has been facing a variety of pitchers who are not all major league pitchers nor in mid-season form.
In the spring of 2011, Dave Sappelt hit .564 (22-for-38), along with three homers and 12 RBI for the Cincinnati Reds. The previous year, he had been the Reds minor league hitter of the year. The Reds wisely resisted bringing him north off a hot spring. Later in the year, they did bring him up, and he was totally over-powered by actual big league pitchers who were in mid-season form. He was not really ready.
Sappelt would eventually be a key prospects traded to Theo Epstein's Cubs a year ago for Sean Marshall. This spring, Sappelt has a .494 OPS and headed back to the minors leagues.
Spring training is way too small a sample size to get excited over. Bradley will be the Sox center fielder eventually, but there is no reason to rush the guy. The Sox may surprise this season, but their future is probably not now.
We may not like it, but the Sox are going to have to learn to play, if not Money Ball, at least Smart Ball. Times are changing.