The 6′10″, 225-pound big man previously decommitted from the program in November.
"So many other guys that have really been carrying us all year just didn't have great nights. To have him step us for us in a game like this was huge."
Piacentino blasted three home runs In the Nittany Lions' 13-10 win over Northwestern Sunday.
The sophomore led the Nittany Lions with 31 points in the win Sunday night.
Penn State field hockey (1-2) won in a double overtime shootout against Northwestern on Friday, but fell to Iowa in a defensive battle Sunday.
Penn State played aggressively against Michigan State, with notable goals by Ally Schlegel and Elle Kershner.