but did not show signs to me of being a true feature back and star in this league.

We were watching different guys, apparently.
If you think he'll become the focal point of the AZ offense and garner 350+ touches a year, yeah we were watching different guys.
Do you think this way because he lacks the skill or because will not be given the oportunity from Whisenhunt?

Given some statistics, I think the answer to that question is clear. First off, his 4.5 YPC average is very good (it's tied for 11th in RBs with at least 150 carries - one of the guys he's tied with in YPC has the initials "MJD"). If he were to get 20-25 carries a game instead of 15-18, his number of games over 100 yards would be fairly high. Secondly, there's a stat called "YCo/Att" - Yards after contact per attempt. In RBs with over 150 rushing attempts he is 3rd in the NFL in YCo/Att - behind Michael Turner and Jonathan Stewart. Third, if you take his production over the last 1/2 of the season (minus the last one as ARizona pulled their starters) - he pencils out to about 1200 total yards and 12 TDs on about 250 total touches. 12 TDs would put him 5th in RBs this season. Also bear in mind that in the beginning of the season, Beannie wasn't even getting all the goal line carries. Fourth, his yards per reception is very good (11.9) his catch % aint to bad either (12 of 16 targets, which is a better catch % than CJ, Forte and MJD) - he's just been underused in that regard.
I think Wells has all the tools to become an excellent feature back in the NFL. It all comes down to whether or not the Cardinals will ever use hime enough to take advantage of his skills. Once again, the Cardinals were
dead last in rushing attempts per game - despite being 10-6 (they were leading in many games) and having the 11th highest scoring offense in the league (some of those games they won, they were up quite a bit). The Cardinals were in the middle of the pack in terms of team YPC compared to the rest of the league (i.e. their O-line run-blocking isn't horrible).
My point is simply that given his current (second half of the season) usage, Wells will be a solid RB2, giving you 80+ total yards/game and a TD more often than not. If Wisenhunt wisens up and uses him more (even just a half dozen touches per game more) - you could, given his production rates, very easily have an RB1 on your hands.