NBA

Knicks shocker: Mills replaces Grunwald as GM

In a shocking shake-up to the Knicks front office four days before the start of training camp, Steve Mills is back and Glen Grunwald is out.

Mills, the former Garden president whose claim to fame was hiring Isiah Thomas in 2003, has been named the team’s president and general manager. Mills replaces Grunwald, who will remain with the organization as an “adviser” and likely will not be seen at training camp.

The move also has ramifications for coach Mike Woodson. He has a team option for 2014-15 and no longer has the allegiance of Grunwald, his former college teammate at Indiana.

The impetus for the change by owner James Dolan is realizing the club is in store for a major shake-up by the summer of 2015, when the franchise could have a ton of salary-cap space. Dolan prefers a heavier hitter, such as the more charismatic Mills, who had been the top candidate to run the NBA Players Association, to oversee the process. That overhaul may start next summer, when Carmelo Anthony is likely to opt out of his deal to become a free agent, and Amar’e Stoudemire and Tyson Chandler enter the final year of their contracts.

Dolan and Mills were at the Knicks’ Westchester facility to speak with players about the move Wednesday.

But the timing of this change seems illogical and cold. The low-key Grunwald found out about the change this week after making his final transaction — signing Cole Aldrich — in a summer of moves aimed at competing for the 2014 title.

Dolan wasn’t willing to wait to see if Grunwald’s tinkering pans out. Tuesday, Dolan wouldn’t answer the question of whether the Knicks are better than the Nets. His actions a day later may have answered it.

Mills is well-regarded around the NBA as having strong ties with players, agents and coaches as a former bigwig in the league office. But when Mills was helping run the Knicks with GM Scott Layden, a source told The Post he was behind the ill-fated Antonio McDyess draft-night trade in 2002.

“Glen’s popular,’’ one NBA executive said. “I like him. I’m shocked like everyone else.’’

The Grunwald demotion is not a precursor to the return of Thomas, who also has his eyes on the players union job. Mills testified in the Anucha Browne Sanders sexual harassment suit on Thomas’ behalf and was accused of looking the other way. However, Mills and Thomas aren’t close.

Mills left the Garden in May 2009, shortly after Donnie Walsh came aboard. At the time, Mills’ role had been reduced to marketing and business.

“I am pleased to be able to welcome Steve back to the Knicks,” Dolan said in a statement. “He is a well-respected sports executive with a strong background in basketball, as well as a familiarity with NBA operations and our company. We look forward to his leadership and believe he is the right person to help us reach our ultimate goal of winning an NBA championship.

“We are grateful for Glen’s many years of valuable service and pleased that he will remain with the organization.”

Mills is close friends with Knicks assistant GM Allan Houston, who should have more power entrusted in him. Mills has never run a draft or day-to-day basketball operations, but he will keep personnel directors John Gabriel and Mark Warkentien.

Mills and Houston figure to be the point men in recruiting marquee free agents. The 2015 free-agent class includes Kevin Love, LaMarcus Aldridge, Rajon Rondo, David West, Brook Lopez and LeBron James (if he doesn’t opt out of his contract after the 2013-14 season).

The Knicks begin training camp Monday. Dolan clearly was not satisfied with the Knicks’ second-round playoff exit and may not be enamored with the summer overhaul that have some pegging his team as the fifth-best in the East. There also is little financial flexibility to enhance the roster this season.

However, Grunwald’s performance can be viewed as solid. He finished third in NBA Executive of the Year balloting last season after building a team that won its first Atlantic Division title since 1994.

When the Knicks named Grunwald permanent GM after the 2011-12 season, it was noteworthy he didn’t get the title of president, as Walsh and Thomas had previously. Dolan also didn’t want Grunwald, talking to the media and kept him mostly out of sight. The Knicks feel Mills has more cachet and influence on several levels, and he will be much more visible than Grunwald.

“I want to thank Jim for this opportunity to return in this important position,” Mills said in a statement. “It is an honor and a privilege to work for such a storied franchise and I look forward to doing whatever it takes to make the Knicks a successful franchise and a team that fans can be proud of, both now and in the future.”