Well, for what it's worth, I don't anticipate Mendenhall being in Arizona next-year. I mean, it can happen but I don't think he's doing anything special that a young Rookie couldn't bring to the table. I expect Ellington to be in a committee with a Rookie come this time next year.
Mendenhall: 186 Carries / 577 Yards / 3.1 YPC
Ellington: 94 Carries / 558 Yards / 5.9 YPC
Give half of Mendenhall's carries to Ellington and the other half to Stephan Taylor / whatever Rookie they draft to fill the empty hole.
(Ellington's a definite sleeper for next-year. Especially in PPR, don't be surprised when it happens.)
While I agree that Mendenhall will not be brought back, I suspect they either spend a high draft pick on a player or sign a prominent free agent, with the intention of this player taking over the Mendenhall role.
If it is a rookie, then sure, Ellington makes the cut as a sleeper next year (I like to bet against rookies), but if they bring in a proven talent, who is better than Mendenhall, then I don't think I'll waste even a late pick on Ellington who will probably carry enough name recognition to get nabbed earlier than I would like.
Arizona isn't going to magically turn into New Orleans. Arians has adapted a bit, but still through 14 games the Arizona RBs only have 67 receptions. The only way Ellington becomes a weekly play is if they draft a rookie to fill the void and the rookie falls flat and they have to lean on Ellington. Thus, sleeper status. But I don't like the chances of this. Arians will continue to split the load. I think a realistic
upside expectation next year is 10 carries and 3 receptions. Which could net him a low RB2 finish if he plays 16 games and other RBs get hurt, but he's not a guy you really want to be starting weekly at RB2. If they actually get some talent in there to replace Mendenhall then we're probably looking at 6 carries and 2 receptions in which case you just wasted that 11th round pick - no big loss but there will probably be guys with more than 10/3 upside in the same vicinity next year.
Unless they let Mendenhall walk and totally ignore the RB position in the offseason (unlikely) then Ellington will probably be nothing more than a very, very weak flex play next year. If he were on a different team where he could see 60+ receptions then it might be a different story.