Reason No. 2 – Alexander Mattison does not have game-breaking speed.
This is another example of a perk, so to speak.
At the 2017 NFL Combine, Dalvin Cook ran a 40-yard dash of 4.50 seconds. This places him solidly in the conversation with running backs such as David Johnson, LeSean McCoy, Miles Sanders, and Leonard Fournette. It’s top-level speed, but it is just a notch below that of Chris Johnson and Adrian Peterson, for example.
Speed is critical for rather obvious reasons in an offense. Dalvin provides it. Agility is also vital for a tailback, but it is not as easy as to quantify as speed. Dalvin possesses imposing agility–so does Alexander Mattison.
There is a noticeable drop-off in speed that the Vikings will observe if Mattison is the every-down running back. At the 2019 NFL Combine, Mattison ran a 4.67 40 yard-dash. Although that is certainly not poor, it does place him a tier decidedly below Cook. In fact, Mattison’s 40-time is identical to that of Chicago Bears quarterback Mitchell Trubisky at the same combine. Others recording this exact 40-time through the years include tight ends Hayden Hurst and Mark Andrews.
Speed is not an end-all virtue, but it does matter–and Cook is assuredly faster.
Oh, and for reference, and the other Vikings running back, Mike Boone, is faster than both Mattison and Cook.