Hayes was rated as a four-star recruit out of high school.
Askew is the 14th player to commit to the Nittany Lions this cycle.
The Glenside, Pennsylvania, native appeared in 12 games this season with the Mountaineers, recording 12 tackles and one tackle for loss as a true freshman.
Freddie Dilione V led the way with 25 points, and Melih Tunca added 14 points off the bench.
Wallace returns to Happy Valley with two years of eligibility.
Riker is the sixth offensive lineman to transfer to the Nittany Lions this offseason.