I think its a little premature to label him either way. The first 10 games of the year were against exceedingly soft competition while the last 6 will be against exceedingly difficult competition. So far so good but 4 more to go. We'll have a better idea in a few more weeks after seeing how he fares through a full season and post season.
In fairness, not getting it to Kittle may be as much the coaching staffs fault. Ive been to dozens of games in weather like that. In a bad weather game like that you gotta get the ball to your TE. Thats how you move the chains and sustain drives. When you have one as good as Kittle that is particularly true.