He already added weight to get to 250. I worry about how much weight that he can put on and still maintain his best assets, his quick first step and speed. I agree, his height is fine.
As a comparison at DE, look at Jarvis Moss. He was underweight at 6-6 1/2 and 250 pounds, now up to 265. He is nearing total first round bust status, and will be there after the Broncos release him later this month, as rumored.
Once Maybin takes the field, we'll know if he can get to the QB in the NFL. Let's hope his quick first step and speed will produce Freeney like results and not have his lack of weight produce a Jarvis Moss like bust.