More difficult , yes - but not impossible.
If Miami's other RB's put up better numbers than Cam vs FSU/Clemson/Pitt, and RB's from other teams are putting up better numbers than Cam vs those teams, then you have to wonder why that is.
I would say you can see the tendencies in Cam's game - both good and bad - In the UAB/Louisville/FSU game that are indicators of why he didn't have great games vs Clemson & Pitt.
Cam is patient at pressing the line, reading the hole (when it's there), and has dangerous speed once he gets through the hole. He can burn a defense.
When the hole isn't there, he struggles to create for himself and IMO too often his instinct is to get to the sideline. This leads to some big plays, but also to some bad losses. And that gets exposed more often vs good Defenses.
His running style is why he continues to be a boom or bust RB.