you said all things being equal, Collins was already bulked up to 230 by the time he was a senior in high school, added another 24 by the time he ran that 4.88. Yeah Lacy ran a reported sub 4.5 40 as well but he has ran over 40 yards, what twice this year?, I think over 30 3 times. Yeldon also has two runs over 40, but 4 over 30 on lesser carries (those of course include the ones going over 40) so he might have more top end speed but weighs less. When you have 4 different guys come out and produce like that (Ingram, Richardson, Lacy, Yeldon) its seems like more of a plug and play type thing rather than Alabama striking gold with 4 different backs. Richardson was supposed to be more talented than Ingram and was super hyped up and he has been pretty slow in the NFL. Alfred Morris 2nd in the league with a 4.67, it doesnt take great top end speed to be great. If Blount wasnt lazy, and could pass block and receive, he would still be producing as a runner at 4.7. LeRon McClain ran for like 800 yards one year and his 40 was 4.88.