User blog comment:Godisme/Shades of the Bond/@comment-1268838-20111130213818/@comment-893506-20111130215747

The badge was said to control his overall spiritual pressure as long as he had it with him, but overall, Ichigo still has trouble controlling his power. Ichimaru even noted that Ichigo's fighting ability suffered greatly because of his lack of resolve to fight Aizen at the time, so it's not that much of a stretch that he still has trouble controlling his own power, especially considering it's been 17 months since he last used his Shinigami powers.

But yeah, once the chaos with Xcution settles down, I'm hoping there's an explanation as to why Ichigo's Shikai and Bankai had changed.