Nobody pulls their starter WITHOUT INJURY, INEFFECTIVENESS, or a HUGE 4TH QUARTER LEAD in meaningful games UNLESS the backup is some sort of package runner A LA BEAU PRIBULA.
To say otherwise is against 99.9999% of what all coaches have done for at least the 42 years I have been alive and 37+ I've been watching the sport.
Nobody prepares their 3rd string with mop up snaps either when the #2 needs them. This is an unfortunate (for PSU) event due to the portal window.
Unless Grunk can run the Beau package, why insert him into a game that is in question randomly?
Nobody with sense got mad about Roberson failing at Iowa in '21. The failure there was 1) not letting Veileaux out of the dog house or 2) not replacing Levis in the portal or 3) the run of Trace-like mobile QBs we 80% recruited until Smolik/Grunk/Kritza.
If we get up on Boise, sure, bring him in. If Grunk can run the zone read or RPO effectively enough that Boise has to respect his legs, try it.
If he's just a pocket passer, let the better do it.