You rifle through your locker. It's weird, all the stuff is your size, and has been worn. You pull out your wallet, and discover a photographic college id card. It's your photo alright. You bang your head on the roof of the locker, and turn your head to look at what you hit your head on. There's a weird symbol painted on the underside of the locker. Part of it looks familiar, there was a doodle on a notebook in Dirk's locker. You dash back to Dirk's locker and retrieve the notebook.
You open the notebook, and flip through the pages. It's Dirk's diary. Your eyes widen as you read about how he had given Luke the magic potion was put inside the jacket he gave you. It's the reason that you spent that last few weeks as Luke's jersey. You read as he records how he picked you out because of your family curse. His plan all along was to transfer the weredog curse to Luke. Come morning, the moonrise should change Luke back into a man, but his mind will be permanently altered by the dog curse. Luke will be totally devoted to his master Dirk, whether or not Luke is a dog or a man. Dirk's goal all along was to own Luke.
From what you've read, Dirk didn't expect you to be human again. That could work to your advantage.
Dirk had convinced Luke that you were a better player than he was, and that he could steal your skills if he changed you into a jersey, and wore you. You don't know whether he stole your skills or not, but he sure stole your curse. You aren't sure if you should feel relieved or not. It occurs to you that if Luke changes back into himself, you might change back into his jersey. You need to figure this out. You grab Dirk's journal, and head for the college library. You need answers fast. The moon will set in just a few hours.