FORT WAYNE – The Colts’ new general manager, Ryan Grigson, said there are roughly “600 coaches in the NFL and we want to find the best one.”

Grigson and owner Jim Irsay decided Tuesday that Jim Caldwell was not the best choice to lead the Colts next season so they fired him after three seasons as head coach.

“We just came to the conclusion that this is best moving forward for the franchise,” Grigson said.

“Mr. Irsay is the steward of this franchise, and I’m here to help him wrap his head around these types of decisions. We’ve been in football our whole lives and a lot of it is about instincts.”

Caldwell went 26-22 in the regular season, including this season’s 2-14 mark, which landed the Colts the top pick in the upcoming draft.

“This was difficult because of my affection for him and knowing what a good man he was,” Irsay said. “That team played hard until the end last year and that was a great credit to (Caldwell).”

Caldwell got the Colts to the Super Bowl after the 2009 season, becoming the fifth rookie coach in NFL history to do so, but they lost to the New Orleans Saints.

“I just want to thank Jim Caldwell and acknowledge all the outstanding things he’s done for this franchise,” Irsay said. “This was a difficult decision. I think that it was based on the feeling that this was a direction the franchise needed to go, and I wanted to make sure that we took all the time we needed to make sure that it was the right decision. Ryan and I had a chance to evaluate the situation thoroughly since he was hired.”

The Colts began this season 0-13, and Caldwell had been in limbo since the Jan. 2 firing of vice chairman Bill Polian and his son, Chris, the vice president and general manager.

Grigson, who had been Philadelphia’s director of player personnel, was hired last Wednesday by the Colts and given a week to determine the fate of Caldwell.

“Change sometimes isn’t always the easiest transition to make, but it’s part of this game, part of this league and part of the steps needed to get going in this new era of Colts football,” said Grigson, who has spoken with ex-St. Louis head coach Steve Spagnuolo about the Colts’ vacant defensive coordinator position.

There are several assistant coaches, including offensive coordinator Clyde Christensen, awaiting decisions on their fate.

The Colts are in a period of transition with their roster. They must decide by March 8 whether to pick up a $28 million option on four-time MVP quarterback Peyton Manning, who missed all of this season after three neck surgeries in 19 months. Center Jeff Saturday, receiver Reggie Wayne and defensive end Robert Mathis are all on expiring contracts.

“It’s a big change for the franchise,” Irsay said. “At the same time, there are players, other coaches, other people on the staff that will go forward into a new day and go about the work of building for 2012.”

There’s also the No. 1 draft pick, which could be used on Stanford quarterback Andrew Luck, whose presence might affect the need for Manning.

“I really think we’re going to get an outstanding head coach to lead us going forward,” Irsay said.

jcohn@jg.net