Is there a source confirming that?
Nope, just a theory.
It's not WSJ who ruined Bleach, it's Kubo himself. Guys at JUMP would have cancelled Bleach a LONG time ago considering its extremely low weekly rankings by fans for the last couple of years, but they did not because it once was a beloved series and did let the author to wrap it up... But now, when even the Tankōbon sales dropped drastically, keeping the manga running had absolutely no benefit for the magazine and they basically axed it.
If it weren't for the fame and glory Bleach once held, we'd have witnessed its cancellation long ago.
Well, from the way he wrote the manga it's quite clear that there's a drastic difference in quality of both story telling and presentation in general when we compare the stuff before Fullbring and after. Seeing how, up to the point of Aizen's defeat, Kubo had a clear plan for the story and tied pretty much all important loose ends I'm lead to assume that he planned for the manga to end there. (Hence Ichigo losing his powers, big bad getting defeated and everything going back to normal.) I assume that then JUMP didn't feel like ending it there as at the time, the anime was still strong, the profit was nice and we all know JUMP (like any other massive publisher) values profit over one's creative vision.
They have the power to choose which series will continue and which one will not and even with the creator reluctant to continue, given enough motivation, they could nag them into submission. Just your typical editorial meddling that turns a good manga into a milk cow.
The drastic change of focus in the later parts and an infinite amount of asspulls makes me think that Kubo just went along for the sake of it. Ichigo gets his powers out of nowhere, a new OP villain appears, instert cliche plot twists that add nothing more than forced drama in a desparate attempt to keep the stuff somewhat alive (*cough* I'm your father *cough*) - nothing felt the same really.
