Konan Niederhauser will leave the Nittany Lions after one year with the program.
Penn State is 2-0 against the Stags all-time.
The Nittany Lions will play Nebraska, Maryland, and Ohio State twice.
Matthews scored nine goals on 16 shots in three tournament games.
Fleming's girlfriend, Alyssa Boyd, was pronounced dead at the scene.
Lee was a key reliever for the Nittany Lions last season.