From the beginning, Zaraki fights for fun. His ennemies dying(or not; Ikkaku/Ichigo) is a mere result of his "hobby". I think Kenpachi just doesn't fight seriously, he isn't in for the kill, he's in for the thrill. When he lost against Ichigo he just got careless and got overpowered for a split second.
About what's up ahead, he stops Tesla then Noitra attacks without showing any form of effort. The match is settled it's obvious Kenpachi will own Noitra's ass in a flash. Yachiru fighting him though, could be way more interesting.
Please no more, Icy Midget is everywhere. Movie, OVAs, fillers ... enough.t I really wanted to see Hitsugaya again but I