Bill Grier coached San Diego to an upset of UConn in the 2008 NCAA Tournament, his first season as Toreros coach.
It never got better than that for Grier, who was fired Monday after going 117-144 in eight seasons.
"Although we improved a little recently, we didn't get to the place we wanted to," athletic director Ky Snyder said.
The AD said he needed to "see some steady progress and I didn't see it build to where I wanted to."
The Toreros were 15-16 this season.
"I'm more disappointed than anyone that we didn't win more games, but I know we did things the right way," Grier said in a statement.
Grier had been an assistant at Gonzaga for 16 years before replacing the fired Brad Holland in March 2007. The Toreros upset UConn in the NCAA Tournament in his first season — with players recruited by Holland — before losing to Western Kentucky and finishing 22-14.
That was the first NCAA Tournament win by a Division I program in San Diego. San Diego State didn't pick up its first NCAA Tournament victory until three years later.
Grier never came close to replicating that success.
Weeks after the Toreros beat UConn, Grier interviewed for the vacant Oregon State job but then decided to remain at USD.
The Toreros tumbled to 6-24 in 2010-11, the second of four straight losing seasons.
The program was buffeted after Brandon Johnson was indicted on game-fixing charges related to the 2009-10 season.
Snyder said Grier "rebuilt the character" of the program "when Brandon Johnson put a black eye on the program."
"This is a tough business because I think the world of Bill, his staff and families.
Snyder wouldn't discuss candidates, who could include former Toreros players with NBA coaching experience, Eric Musselman and Mike Brown. Musselman, now on LSU's staff, had stints as head coach with Golden State and Sacramento. Brown coached both the Cleveland Cavaliers and Los Angeles Lakers.
Under Grier, three Toreros players became program career leaders — Johnny Dee in scoring (2,046 points), Christopher Anderson in assists (757) and steals (254), and junior center Jito Kok in blocked shots (195).