Yes, it is terrific to have a RB like Gurley who is a threat in the run or the pass.
And yet, that's an awful lot of eggs in one basket, when that basket is not called QB.
I think the best solution is to have a stable of RB specialists. At the least, behind the All-purpose RB, you must have a variety of RB types. They 3rd down blocker. The Reciever out of the backfield. The quick and darting kind and the power back.
The Pats have made RB an art form of with a stable of inexpensive, disposable specialists. No one RB is the straw that stirs the drink. Any one of them can go down and the Pats are not particularly handicapped.
Can you imagine if Gurley were to go down for a couple of games?
We see what happened when Mr. All-Purpose Ezekiel Elliott got suspended; the Cowboy's offense went into a death spiral.
Not trying to be negative. Just saying that the game has changed and I'm not sure that the need for the "Complete" back is as great, or as wise, as it used to be.