The Arizona Cardinals added a new offensive toy for head coach Bruce Arians to play with in drafting running back David Johnson. For a coach that loves flexibility, he now has a pair of running backs who fit the mold perfectly.

Johnson, who started his college career as a receiver, is a very good pass catcher. He runs well and understands running routes. Andre Ellington has already been praised numerous times about his ability to play receiver. Carson Palmer has joked about wanting him there at the position full time.

Why does this matter? According to Mike Jurecki, the Cardinals are discussing using both running backs on the field at the same time and also as receivers. This makes sense, as it will cause all sorts of mismatches for defenses.

Both could be in the backfield and one could motion out. Both could line up at receiver and one motions back in to the backfield. There could be any sort of combination of ideas.

The Cardinals wanted to draft a bigger running back. They got one in Johnson, who measures 6-1 and weighs 225 pounds. But while they got a bigger guy, they also got someone just as versatile as Ellington in terms of offensive threat.

Imagine Larry Fitzgerald, Michael Floyd, John Brown, Ellington and Johnson on the field all at once. Is there a team who could cover all five of them well?

Assuming Ellington returns to full health, have the Cardinals ever had as exciting a running back duo that you can remember?