Wrist injuries can and usually do sap your power. I had a friend that had a similar wrist problem a few years ago and never went on the DL, played 113 games, yet had by far his worst power year of his career.
That year he hit 8 HR in 113 games. The previous five years, all in AAA, his HR totals were 17, 13, 18, 18 and 21 the year before the injury.
That kind of wrist injury will only go away with a long period of rest, yet it does not keep you from being able to play.
I would definitely chalk up Joe B's lack of power to the wrist injury.
we'll he did only have one before it.