So if you have XB at ss,Holt at 3b, Betts in CF(who has just started playing cf a couple of weeks ago), Pedroia at 2b, Nava in RF?, Gomes in LF?, Napoli 1B, AJP at Catcher. This might be the worse defense in the history of baseball.
And Bradley is not my Pet, but I do enjoy watching excellent defense. As I stated before, I try not to judge rookies who have had success in the minors until the have reached 1000 abs. JBJ has been successful at every level and I expect him to make the necessary adjustment to be successful.
WMB 2012 286 pa's 288/325/509
since 2012 456 pa's 222/277/408
I think we can agree that at the very best WMB is average(this is being generous) at playing defense at 3b . fangraphs has WMB at .3 fwar
JBJ 2014 265 pa's 209/289/298
The defensive metrics love JBJ, in 2014 per fangraphs he's been worth .6 fwar(which is tied for 5th on the team)
I guess it depends on what you want. If you value obp and elite defense the obvious choice is JBJ, If you value a HR every once in awhile then you would go with WMB.
PS I still have hope for WMB, but to call out JBJ and support WMB is ridiculous.