He's only 21. He just had a pretty remarkable rookie season, especially given the role of being #2 center for the first 50 games. His point totals were pretty close to Toffoli and Pearson those 50 games and they both got PP time and Kempe didn't. Kempe has the ability, shot and speed to be top 6 now and should be. He should also get PP time. He's produced on Team Sweden on the PP.
He should add another 10 lbs of muscle...looks like he can add 15, but just adding some muscle will give him more of a power game too. Consider when Brown, Kopitar, and even Doughty got bigger, their games actually went down somewhat. Have heard all of them lost a few pounds and were actually better...its about conditioning and not bulking too much...slows players down often just a fraction of a second and that makes a difference today.