SANTA CLARA — Yet another 49ers player from the team’s glory days weighed in on Jim Harbaugh’s locker room culture this week.

But this one ran a reverse.

Roger Craig called criticism of Harbaugh’s leadership “a bunch of crap” and said the coach’s growing number of second-guessers should “keep their mouths shut.”

“There is a code of respect for your team, for your organization,” Craig said Friday. “People tend to forget, he changed our whole culture and got us winning again. Three straight NFC Championship games. A stadium got built because of what he did.”

The four-time Pro Bowl selection called the Bay Area News Group out of the blue on Friday in response to a steady stream of reports casting Harbaugh in a negative light. Craig repeatedly stressed that he was not calling out former teammates Steve Young and Jerry Rice, who stirred the pot recently by wondering about the 49ers’ chemistry.

Young said the 49ers “look broken” while Rice went so far as to tell Pro Football Now that Harbaugh’s murky contract future might be “starting to wear and tear on the team and it’s taking its toll.”

Craig played down those comments and said he’s more troubled by the way the media, television commentators and fans have turned on a coach who is 40-15-1 since taking over in 2011. He said the vibe of the locker room overshadows the real reason for the team’s disappointing 4-4 first half — injuries to players such linebacker NaVorro Bowman, linebacker Patrick Willis, tight end Vernon Davis and the suspension of linebacker Aldon Smith.

You can’t pin that on Harbaugh, he said.

“I’d be mad as hell if someone was talking about my coach like that,” Craig said. “He hasn’t lost his focus on this team, trust me. That’s not in his character. That’s not in his DNA. People are taking their shots, but they shouldn’t make assumptions when they don’t really know what’s going on in the locker room.”

Numerous reports this season have indicated that Harbaugh’s abrasive style is wearing thin on players. Craig recalled that Bill Walsh, though revered now, could be hard on players, too. That’s why all this talk about the team’s mood gets on Craig’s nerves.

“If you’re looking for a pat on the back every time out, you’re in the wrong business,” said Craig, now an executive at the TIBCO Software company in Palo Alto. “You’re not there for personal relationships. As a player, it’s your job to show up every Sunday and do whatever you can to win.

“They’re paying you a lot of money — a lot of money. I always respected the coaches but you weren’t there to be their buddy. You don’t want someone to be soft and be your best friend? Hell no. If I’m doing something wrong, let me know.”

The 49ers lost 13-10 at home to the St. Louis Rams last week in one of the worst performances of the Harbaugh era. Offensive tackle Joe Staley summed up the day by saying the team made dumb “penalties, dumb blocks, dumb techniques and dumb schemes.”

Offensive coordinator Greg Roman came under fire for not simply handing the ball to Frank Gore during a disastrous goal-line sequence that ended with Colin Kaepernick fumbling the ball away in the game’s final seconds.

But Craig, an avid Gore supporter, couldn’t bring himself to question that move, either.

“It’s easy to say, ‘Just give the ball to the running back,”’ he said. “But (Rams coach) Jeff Fisher is a great coach. The Rams guessed right, and that’s the way it’s going to go sometimes.”

Craig said current crossroads for the 49ers’ season reminds him of a pivotal juncture in 1988. That team lost back-to-back games, to the Phoenix Cardinals and Los Angeles Raiders, and fell to 6-5.

“People were counting us, saying we were through,” he said. “That’s when Ronnie Lott called a team meeting and kicked all the coaches out. He said something. I said something. Everybody had their say and we took ownership of our team, became the CEOs.

“The message was: How do we get on track?”

The 49ers went on to squeak into the playoffs at 10-6 before beating the Cincinnati Bengals in Super Bowl XXIII.

Craig said the current 49ers should adopt the same mindset.

“Don’t point fingers. Just stay together and have one heartbeat starting in New Orleans (on Sunday) and keep it going,” he said. “The outside stuff will eat you up.”

Contact Daniel Brown at dbrown@mercurynews.com. Follow him on Twitter at twitter.com/MercBrownie.