After drafting Ellington in the sixth round two years ago, the team's coaching staff expressed concerns about overworking the former Clemson star due to his slight build and thin hips.
Ellington's body predictably broke down under that excessive workload, resulting in dramatic decline in yards per carry from 5.5 as a rookie to 3.3 in 2014.
The scat back played with a "split tendon" in his foot for three months until sports hernia surgery ended his season in early December.
Although Arians maintains that Ellington is "still the focal point of our offense," Keim acknowledged a need to "shore up" the position this offseason, per the team's official website.
Keim believes Ellington is a feature back from a skill-set standpoint, but concedes durability is an issue.
"When I went back and looked at some of the cut-ups, you can't deny his skills -- his feet, his acceleration -- he's got dynamic skills and game-changing speed," Keim said, via ArizonaSports.com. "That being said, it remains to be seen whether he can stay healthy for a full season. To me, that's why this offseason is so big for him.
"He's got to get bigger and stronger in the weight room and he's got to prove he can stay healthy through a full 16-game season."
Ellington doesn't run well between the tackles and isn't built for 20 touches per game. Even if he spends the offseason in the weight room, the Cardinals need to add a "thunder" to his "lightning" for a complementary backfield tandem.