Mostella, who hails from Alabama, is now at La Porte (Ind.) La Lumiere. At 6-foot-2 Mostella can really put points on the board in a hurry, and now will play for Travis Ford.
Alan Huss of La Lumiere has been very impressed with Mostella this season.
"He is as good a scorer as I have been around," said Huss. "He can make shots, is a great athlete, and is working hard at being more consistent every day."
Mostella was thought to be someone who would wait until the Spring signing period, but he informed Scout.com on Saturday evening that was no longer the case.
"I've been talking to my parents and my AAU coach, and they know where they want me to go and what is the best place for me, so I am just doing it for all my people," said Mostella.
Mostella hasn't yet visited Oklahoma State, but he plans to do so during the winter.
This is the fifth commitment for Oklahoma State in the 2013 class.