Stutzle doesn't need to get bigger, he needs to get stronger, there's a slight difference. Sometimes he gets bumped off the puck like he's an adolescent. He needs to know when to use his skill, when to expect a hit. We've seen him fall on his ass doing a 360 twirl because he whiffs on a shot or even pass. It's just inexperience and improving balance workouts, core, conditioning etc..
We have also seen him play a physical brand of hockey, he can really injure himself if he underestimates his strength down the middle of the ice trying to dangle and gets lined up by a much stronger defender.