He's a great player, but the way he plays (as well as his usage) prevents him from being much better.
The Jets have a interesting issue... Connor is (right now) the most dangerous offensive weapon; Scheifele is the most talented player on the team; Wheeler somehow makes Scheifele produce more; Ehlers has the best "natural" skill set; Laine has the highest offensive upside; and I'll toss in Harkins simply because his north-south game is the perfect compliment to the east-west players on the top two lines. And yet, despite all this, they can't seem to score goals anymore.
The problem, to me, is the absence of a legitimate number two offensive center. Copp ain't it, Roso ain't it, Lowry and Cody Eakin sure as heck ain't it, and Wheeler is needed (right now) to spark Scheifele. If we had a good second line center, I think all of the other pieces would fall into place.