Walsh said he informed Thomas of the decision Friday.
"It's very difficult to be the coach and general manager," he said. "Maybe it was too much."
Walsh took over Thomas' role as team president April 2, and his first big decision was to change coaches as he begins the process of turning around a team that never won a playoff game in Thomas' tenure.
"I just believe a new voice, a new coach, is necessary to change the direction of the team," Walsh said.
The Knicks finished 23-59, matching the franchise record for losses, in their seventh straight losing season.
"I can't tell you really where we failed," Walsh said. "The bottom line is we haven't won, and the team didn't look like it was motivated to try to win."
Two of those 59-loss debacles came in the last three years, when the Knicks solidified themselves as the NBA's most dysfunctional franchise with poor play on the court and embarrassing behavior off it.
This season alone, Thomas was found to have sexually harassed a former team employee, feuded with point guard Stephon Marbury and benched center Eddy Curry - the players Thomas acquired in the two biggest of a number of moves that never panned out.
Walsh wants a new coach in place by the draft in June, when the Knicks will finally have their lottery pick again after handing over their last two to Chicago in the Curry trade.
"Obviously, when you're losing, there has to be a culture change," he said. "There's no easy answer. ... We've got to work 24-7 to become competitive."
And Thomas will be a part of that.
"I feel like some of the bigger events that happened on the way with Isiah overshadowed some of the good things" that he accomplished, Walsh said.
"I will be in touch with Isiah a lot," he said.
Thomas is 187-223 as an NBA coach, leading the Indiana Pacers to the playoffs in three straight years from 2000-03. Larry Bird fired him after becoming team president, a move Walsh - who had hired Thomas as coach - was originally against but eventually went along with.
Thomas was hired as the Knicks' team president on Dec. 22, 2003, and he acquired Marbury from Phoenix weeks later. The Knicks made the playoffs that season, getting swept by New Jersey, but haven't gone back despite their annual spot atop the league's highest payroll list.
Though the salary cap was already out of whack by the time Thomas arrived, he didn't help matters with some questionable moves. He gave a $30 million contract in the summer of 2005 to center Jerome James, a career 4.3 points per game scorer who hasn't been healthy or productive, and seems bothered by neither. A year later, Thomas used his mid-level exception on Jared Jeffries, who has limited offensive skills.
Still, Madison Square Garden chairman James Dolan remained confident in Thomas, even making him coach in June 2006 after firing Larry Brown following one season. But that came with an ultimatum, as Dolan warned Thomas to show "evident progress" in one season or be fired from both positions.
The Knicks went 33-49 last season, but that was good enough for Dolan. He rewarded Thomas with a multiyear contract extension with more than a month left after New York moved into eighth place, but the Knicks collapsed under a series of injuries and missed the postseason.
Things went poorly this season from the time training camp opened.
The jury came back with its verdict that day, finding that Thomas and MSG sexually harassed former team executive Anucha Browne Sanders and ordering the company to pay $11.6 million in damages. Criticized by Al Sharpton and Rutgers women's coach C. Vivian Stringer for comments he made in his taped deposition, Thomas seemed downcast during most of training camp - and never had much reason for better spirits when the season began.
The Knicks started 2-1, then dropped eight in a row as the Thomas-Marbury feud sent the season spiraling out of control. Marbury responded to Thomas' plans to bench him by skipping a game in Phoenix, and the players reportedly voted to make Marbury sit out a game when he returned. Instead, Thomas played the point guard more than 33 minutes off the bench in a game in Los Angeles against the Clippers.
It soon became obvious that Thomas' draft night acquisition of Zach Randolph had set back Curry, who lost his confidence and later his starting job. Speculation was rampant by Thanksgiving that Thomas' job was in jeopardy, and it only heated up after the Knicks' nationally televised 104-59 loss at Boston on Nov. 29.
Chants of "Fire Isiah!" sometimes started minutes after home games, and even Dolan's strong relationship with Thomas couldn't convince people the coach would last.
