I'm just watching a few Cecil Collins LSU highlights to remember how he was in college, as it was a long time ago.
Cecil was a very straight line runner that did not make anyone miss, but rather aimed for contact and hoped to spin off of it or give a limp leg for extra yards. The tendency was consistent as clockwork. His instincts for avoiding tacklers and running to daylight were really pretty poor. Even when he's got an angle he'd rather run through you than around you. He had some balance issues when he tried to make any cuts to get away from wreckage, and that could be part of the reason, as he wasn't comfortable making any cuts at speed for fear of losing his balance, and would rather just run through the contact. Some players can get away with that style if they've got the power and size to back it up. In college he had an impressive ability to bull through contact, kind of reminiscent of Adrian Peterson a little. He seemed to have really good speed, and an excellent build, but the overall size/speed ratio I don't find to be as compelling as I do Jonas Gray. As it's been pointed out, Cecil was only about 207 lbs and I think ultimately that had an impact on whether he was able to bull through contact at the NFL level the way he did at the NCAA level. Adrian Peterson was not only bigger which has allowed his vicious run-through-contact nature to translate, but he's also always been more proficient at cutting away from defenders.
All that said, it's really easy to nitpick when you know the guy was not successful at the next level. Still, I don't know if I see stylistic comparisons between Cecil Collins and Jonas Gray. I think if I were to make a stylistic comparison between Cecil Collins and someone in this Draft, it would be closer to Cyrus Gray than Jonas Gray.