2.1 dWAR for Bradley Jr. If Boston was a better offensive team, they could manage him in the lineup. Unfortunately, the big number for Boston is -0.3 oWAR, which they cannot afford to carry in the lineup.
In addition, Boston wants to see what they have in Mookie Betts and Brock Holt in CF, rather than continue to waste ABs on Jackie Bradley Jr. in Boston, as he is seen more as a 4th outfielder or defensive replacement, and likely will be dealt this offseason as part of a package for a bat.. David Ortiz isn't going to last forever, and they desperately need offensive help in Boston if they're going to contend in 2015 and beyond.