You sign with the school, not the coach, son
That, in a nutshell, is how the National Letter of Intent will be enforced at NCAA member schools moving forward according to a report by The Sporting News:
The National Letter of Intent Policy and Review Committee sent a memo to member schools Thursday announcing that “institutions should be aware they are prohibited from establishing any additional conditions associated with the NLI agreement in advance of a prospective student-athlete signing the NLI.”
A copy of the memo was provided to Sporting News by a Division I basketball coach. The memo declares that if any institution or its employees “offer additional conditions, the prospective student-athlete’s NLI is subject to being declared null and void along with possible institutional penalties.” The memo does not state what sort of penalties might be enforced.
Obtaining a release from a Letter of Intent has become commonplace following coaching changes: both Devin Ebanks and Terrell Holloway were released from IU after Kelvin Sampson was fired. This past spring, Xavier Henry invoked a clause in his LOI with Memphis after John Calipari left the school and bolted for Kansas.


