OK, I'll take the geek-bait.
As Ursus pointed out, Force = Mass times Acceleration, which is a function of the change in velocity over time - irrelevant in this case. We don't care how Tank's velocity changes over time - we simply care how much kinetic energy he's carrying when we hit him (or when he hits us, as the case may be - an equal amount of kinetic energy would be required to stop him).
Kinetic energy is defined in terms of Joules and is a function of his mass in kg (known) and his velocity in m/s (speculated). The formula is Ek=1/2mv^2. That is: Kinetic Energy = 1/2 the object's mass times it's velocity squared.
Did some rough excel calculations, and at 350lbs (158.7572kg) and a claimed 4.9 40 (7.464126 m/s) this guy is carrying 4422.43345 joules of kinetic energy. To put that into perspective, a 220-230lb RB (comparable to MI, TR and EL) would have to run about a 3.9 40 to equal the energy, which as we all know, is faster than anyone has ever run in the history of the human race. Even if our behemoth here is running a much slower 6.0 40, as some have speculated, he's still producing 2949.51742 joules of kinetic energy, equivalent to MI, TR and EL running about a 4.8 40. For what it's worth, they all run a 40 in the 4.45-4.55 range, producing 3300 to 3600 joules of kinetic energy. Truth is, roly poly here is probably running somewhere between the two extremes in the 5.2 - 5.5 range or there abouts and surpassing MI, TR and EL with 3500-3900 joules of kinetic energy. But his slower speed makes him easier for college level athletes to catch even if he is very difficult to stop.
Great short yardage option at fullback. But if he's got good hands and feet, probably still better suited for fulltime DT work unless he's signed by a team that runs an I and features a fulltime fullback. That team, of course, isn't Hawaii.
Edit: A 260lb linebacker would have to be bringing around 4.6 speed to not get run over. Nico's measurables? 260lbs, 4.62.