Sony's speed??

I have seen it mentioned a couple of times how Sony does not have good to great speed? I could have sworn he was in the low 4.5 range at the combine? I remember him in Chubb in the backfield in Georgia and unless y memory is failing me. Michel was the better ll around back catching out of the backfield etc. I just think that he was not asked to do that in New England, that went to White??? Am I wrong??