Callahan checks in at 6-foot-6 and 285 pounds and has earned a very early four star rating by Scout.com's recruiting team. He is considered one of the top 100 prospects in the nation according to Scout and was also named to the ESPN 150 Watch list as a junior.
On the field for Chaparral High in Parker, Colorado, Callahan is a two year starter with All-Conference honors in each of his two varsity years. So what, aside from prototypical size, makes him so effective?
"It starts with my size and ability to overpower my opponents, and I have a good combination of speed and athletic ability as well. I know I need to continue to work on my technique and not just rely on my physical gifts."
Despite the self-assessment, there are plenty of schools who are well into their recruitment of Callahan. Some have even gotten visits over the last few months.
"I have been on unofficial visits to Notre Dame, Michigan, Nebraska, and Colorado. I will more than likely revisit some schools and may make some visits to some SEC and Big 10 schools as well. I know I am going to junior day at Notre Dame."
With so much high major interest, Callahan has no shortage of options. And the Blue Devils have thrown their hat in somewhat.
"I have received several letters from the coaches at Duke, but haven't had time to speak with them directly. The letters are a start, but right now what I know is mainly about their academic reputation and basketball program."
Callahan denies an early leader and says he is looking for a program that "fits" him but also offers top flight academics and a sense of community.