More specifically, I'd say:
QB - McCaffrey - probably, if we need him. Our QBs are always dinged up.
RB - Johnson hopefully just in 1 more, and it'll probably be a single play or something dumb.
WR - I'm sure Chase will play another one or two, but from what I've heard Nance and Houston are still on the scout team so doubt it for them.
TE/WR - Hickman seems to be in line to play, he's got 2 games he can use.
OL - Maaaybe Benhart/Piper, but I'd guess only if there's an injury.
DL - Keem Green should play in all 3, not a freshman though. I'd love to see Robinson, but again probably an injury or blowout of MAryland thing.
LB - Dear Lord I hope so for Henrich and Hannah. But again, feels like only for injury/blowout, maybe special teams.
DB - They've thrown the DBs out for a game or two each on special teams, I expect more of the same. Would be pleasantly surprised to see them on defense but don't expect to.
Other than risking longer term injury, which can happen on any given play in any given game, I am not sure I see the negatives to sending out a Freshman you're going to redshirt out against Wisconsin and Iowa and letting them see first hand what it is going to take in the offseason to be better than them.
If we think we can win, the issue is a freshman not knowing what to do and giving up a back breaking play. Our upperclassman are good enough at doing that, so if it's a higher risk I get the aversion. Frost talked about our narrow margin for error because of talent earlier in the year - if we had more margin for error, I think they would work more freshmen in.