And for that reason I think bxc3 was probably better, although the pawns look weak.

This push emphasises the advantage. If 25.bxc4 then Bxc4 is strong. Black just has to make sure he has an answer for e6. Of course if 25. Qxa2 Rd1 etc.

After this the b4 cannot be saved without abandoning the defence of d1 and e6 is placed firmly under lock and key.

White resigned before awaiting reply. Black is two pawns up with three passed pawns and white has no defence to straightforward plan of pushing the c pawn: 28...c3 29. Rb1 c2 30. Rc1 Rd1+. 28...Bd1 probably works too!