Wow, this just made me so happy.
The flashback just goes to show again that Kise had a pretty mean side that he doesn't display to people he respect. Also there's forever a debate about 1v1s between Kise, Aomine and Akashi that I don't want to get into, but back in Teiko Kise was clearly the weakest of the bunch as he didn't have perfect copy. He just came a long way since then.
PS. Kise too OP they had to nerf him with an injury >.>