Pittsburgh and Syracuse made plans to leave for the Atlantic Coast Conference in September, and West Virginia bolted for the Big 12 the following month. The Big East regrouped by adding Central Florida, Houston, Memphis, SMU and Temple for all sports and Boise State, San Diego State and Navy for football only.
''Our recent expansion efforts have stabilized the conference for the long term, and we are likewise well positioned for our very important upcoming television negotiations,'' Marinatto said in a statement from the conference. ''As a result, I felt this was the right time to step aside and to let someone else lead us through the next chapter of our evolution.''
Marinatto became the third commissioner of the Big East on July 1, 2009. He had served as the conference's senior associate commissioner since 2002 and spent 14 years as the athletic director at Providence College.
''John helped build the Big East into what it is today, and played a critical role in our successful expansion efforts, and for all of that we thank him,'' said Judy Genshaft, President of the University of South Florida and the chair of the conference.
But privately, many in the conference were unhappy by the defections of Pitt and Syracuse, and some blamed Marinatto for being caught off guard.
Former Commissioner Mike Tranghese, who retired in 2008, said his successor ''inherited a very, very difficult situation.''
''I said that when I left that's one of the reasons why I did leave,'' he told The Associated Press on Monday. ''The conference was susceptible to be raided.''