Bayaz & The Bloody Nine [SPOILERS ALL]

Does anyone have a good idea why Joe chose to never have Logen go berserker before Bayaz? When he does he never witnesses it...only Ferro really does on the journey west. The obvious is Bayaz would be forced to kill him. But this seems like an plot hole to me. The whole point is Logen can't control it, yet it's awfully convenient that we never see these two clash. Not because I feel robbed of a good fight, I just think it's a plot hole in a well written work.