Every year it's "he's still young" and every year there's little to marginal improvement. He still seems disinterested when he doesn't have the puck.
He reminds me of Jeff Skinner, but 20 lbs. smaller. Their career trajectories are on an eerily similar arc. The first four full seasons(since Keller has only played 4 full ones so far):
Skinner: 294 games, 192 points
Keller: 290 games, 191 points
Both have contracts that pay them far too much, but Keller still has a chance to prove he's worth it. I don't see Skinner getting back to the form that got him his deal.