Singletary will fall because of his speed measurements, maybe past the 5th round, but I think the analysts get it wrong when they do this. Too many try to find the perfect all-purpose back and evaluate everyone else accordingly. But being successful in the NFL at runningback is far more than outrunning someone by 2/10th of a second in the 40. You don't see too many runningback breaking out too many 40+ yard runs anyways. Those speedy guys get eaten alive at the line of scrimmage before they get a chance to outrun anyone.
Instead I'd argue the runningback position, at least in the NFL, is more about the 1-5 yard game and consistently being able to knock off chunks of yards here or there. Its about keeping the defense honest to the passing game. With that said, Singletary best trait seems to be finding a crease at the line of scrimmage and getting some tough yards. At times, he bursts through a hole where there seems to be none. He has a good first cut or two that helps him miss the first defender or two, all while not dancing too much, but being able to go north and south.
The stat that proves my point is that he averaged over 5.2 yards per carry this past season, BUT his longest single run was only 44 yards. He didn't get his average Yards Per Carry from a few home-run hits that distorted his numbers, but from consistently knocking off chunks of yards 5+ at a time.
The only thing that concerns me, is that this style of runningback resembles Jordan Howard. Not much in the passing game, but a good complimentary back. I think he will be rated high by this staff, and be one of the best players available if he makes it to the 5th round or later. If he falls late enough I could see us grabbing him even if we decide to go with another running back earlier.