Dominick Stewart was red hot for the Nittany Lions, going 6-8 from deep.
Penn State will miss the Big Ten Tournament in back-to-back years.
Penn State takes their first loss in conference play against the top-ranked Spartans.
McMiller has recorded 13 assists through two games at Penn State.
The Nittany Lions have now lost a double-digit number of matches this season for the first time since 2021.
"Get out there on the road and show a few teams what we're made of."