He had more carries because he was an all down back, and no you can't do that lol. You can't predict that he would've had that many more yards because he didn't. You're generalizing Wadley's entire career like he was great his freshman and sophomore year, which he wasn't. Look at their final year's of production at the RB position.
2017 Wadley
13 games, 252 carries, 1109 yards, 4.4 avg, 10 TD's
2018 Montgomery
12 games, 257 carries, 1216 yards, 4.7 avg, 13 TD's
That last year was Wadley's senior year. His peak. Montgomery would've peaked his senior year but he was busy starting for Chicago. If you want to make the case Wadley was a better receiver / receiving RB, that's perfectly fine because his stats back that up. As a whole running back though, he was not better. That is why Montgomery got those awards and Wadley didn't.
Montgomery was the better runner, Wadley was the better all around running back.