What? No. I can't believe Abarai's training could make him that powerful. If Ichigo is something to go, that training with Division Zero made him weaker. lol
Mask de Masculine after three cheers from James absolutely demolished Bankai Kensei and one-shotted Bankai Rose. By comparison, Released Stark at full power couldn't deal any lasting injuries to Rose even whilst using his wolves. It's important to note that Rose couldn't even react to the laser from Mask, whereas he was keeping up fine with Stark.
So Mask with three cheers is > Released Stark, who is > Shikai Shunsui.
Then Shikai Renji waltzes in and decimates three-cheer Mask with no issues. Mask goes to
four cheers with James' help, knocks away Renji with some One-Mile Arts - but isn't done yet. He even activates
Vollständig, which is pretty comparable to a Resurreccion in terms of a power boost, then seemingly destroys Renji.
Except Renji's Bankai nullifies that and obliterates him with zero issue.
So Bankai Renji >>> Vollständig Mask with four cheers > Mask with four cheers > Shikai Renji >> Mask with three cheers > Released Stark > Shikai Shunsui.
There's no way Shunsui's Bankai could feasibly have him close that large of a gap to Renji's level without some serious bullshit rationalization on Kubo's part. :lol