Well, he hadn't done the Kage Bunshin training with Jiraiya. It does raise the question of "What the fuck was he doing for 3 years??" but everyone's already had a go at that.

I think a week of Frog training using Kage Bunshin could at least teach him some new Frog Jutsu. Maybe, just maybe, he'll emerge as the kind of badass we wanted him to be post-timeskip.