His final season in Columbus saw a new OC install a route tree offense, and Cardale was indeed lost in that offense, as were others. The prior offense was simple. The game against Wisconsin was simple, as Wisconsin wanted to make Ohio State's 3rd string QB beat them... and he did like 50-0 with quickly released lasers that were right on target, but just against man coverage and usually his first read.
Both Cardale and Allen trust their legs too much. Cardale actually has better accuracy, a stronger arm, and a quicker release.
There was no harm in doing what Rex wanted to do... give Cardale three starts. We'll never know what would have happened, but when Phil Rivers is done with LAC, we will find out something...