True, despite the fact that Liffy and possibly even Zoro are now ahead in power than some shichibukai, there has always been a gap in power with the shichibukai members. For instance, the latest chapter revealed that Law (now a shichibukai) can defeat a logia Vice Admiral with ease as well as his whole crew, but failed to even harm the subordinate of a fellow shichibukai Doflamingo. I always knew that Doflamingo was a top shichibukai member, but if Vergo's strength is a testimony at all to Doflamingo's, he is well above the straw hats still. It may have been pre time skip but Kuma was well above the level of the straw hat crew. I still feel that although he might not be capable of annihilating the whole crew now, one on one he would beat any of them.