Well you made an example of the freshman RBs not playing because they're not ready for audibles.
The notion that he, and most other freshman are too young to play meaningful reps, is growing extinct across the NCAA. Younger players are making a bigger difference than ever in college football (with the exception of the OL/DL for the most part). Everyone says stars don't matter, and they don't always, but if you look at the 4/5-star freshman that are playing big time football right now across the country, it's amazing. Coaches are doing a great job of getting the freshman to know the play books faster than I've ever seen before.
DBs/WRs/RBs and even QBs are coming in as freshman/sophomores and making huge impacts, hell, even flirting with heismans lately. The summer camps, private 'football' high schools, and 7 on 7s are probably to thank for this.