Russell Wilson is currently our best running back. Colin Kapernick is a similar runner, and is arguably close to Russell as as scrambler. Their speed in the 40 was almost identical: he, Mariota, and Russell were inches different in the 40.
I heard a rumor that Kap was available, but turned down the 900K that Pete offered him for backup quarterback.
I am just having fun thinking outside of the box. With a second running qb, they could toss the ball back and forth and really spread the defenses. Just imagine having to deal with two running Russells at once. Trick plays galore. Perhaps not trick, but maybe exotic.