I always focus on the positives of Packers draft picks first. I let the negatives, so to speak, show themselves when they actually play a meaningful NFL snap.
To your point, however, he has negatives for sure. He's smaller - though, he does have 195 lbs which is 35 lbs heavier than when he first played at Western Michigan. He's not going to win in his cuts or as the route changes ie double moves - ie he's a bit stiff and those double moves tend to run flat as opposed to sharp. But, he's not going to need to go Outside so I personally don't worry about this. Can he? Sure. But, that's not using him effectively. He should play 80% in the slot, imho. Where he'll win in the slot is with his strength, aggression, catch point etc. He doesn't have anywhere near the agility in those slot routes like a JSN. He just doesn't have that in-route wiggle. But, because of his return prowess, he still know how to make guys miss.
Anyhow, take it or leave it. It makes no difference to me.