STORRS, Conn. — Big East Commissioner John Marinatto resigned Monday after less than three years on the job, admitting he was drained by several high-profile defections and mounting pressure from school presidents upset with the departures.

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.

Marinatto told The Associated Press on Monday that trying to guide the conference through realignment took a physical and mental toll on him.

He said he began talking to the conference presidents in mid-April about stepping down.

“I’ve been running a marathon not only for the last eight months but for the last 2½ years,” he said. “As fulfilling as it can be, it is equally draining. All the assets are in place right now (in the Big East). It’s probably time for a commercialized kind of perspective. Clearly the collegiate model is dead.”

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, having just turned down a television contract offer from ESPN last spring.

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 being raided.”

“When something goes wrong, the person in that chair is the one to take the hit.”

Connecticut President Susan Herbst was asked if the league’s presidents had sought Marinatto’s resignation.

“It was entirely John’s decision,” she said in an email to The Associated Press. “Let me add: He did a stellar job this past year, enabling the Big East to move forward. We are strong now, thanks to his efforts and tireless work in a very fluid environment.”