SCOTTSDALE, Ariz. — Before he could start rehabilitating his image, Barry Bonds needed a different pair of pants.

Bonds walked into the Scottsdale Stadium clubhouse at 8:55 a.m. Monday, eager and a bit nervous about beginning what is probably the most publicized one-week coaching stint in San Francisco Giants history. Within seconds, the white baseball pants in his locker were hustled out of the coaches’ room, swapped for a better-fitting pair.

Bonds is considerably slimmer now, which he says is the result of a newfound passion for cycling but others attribute to seven years away from performance-enhancing drugs. The major league home run leader also smiled more often Monday than anyone could remember, hugging former teammates and shaking hands with veterans and prospects alike. During a 25-minute news conference, the 49-year-old repeatedly turned to manager Bruce Bochy and thanked him for the opportunity.

Day 1 of the second Bonds era was light and cheery — a personality he rarely displayed during his playing days — until the conversation turned to more complex topics.

Asked about the Biogenesis steroid investigation that rocked baseball last year, Bonds chose not to comment. Pushed about Alex Rodriguez, another scandalous slugger, Bonds would say only that the two are friends.

Mark McGwire came clean about his steroid use in 2010 when he returned to the game as a hitting coach for the St. Louis Cardinals. Bonds is keeping the dirty laundry piled in the corner.

“I already went to court, and that’s where I’ll leave it,” he said. “Anything outside of that doesn’t need to be commented on.”

Bonds is back with the Giants for the first time since 2007, but he’s not returning as a Hall of Famer, having fallen well short of admission his first two times on the ballot. He said he “without a doubt” should be enshrined in Cooperstown, but he wasn’t about to fuel the fire for writers who have kept him out.

“You guys are all adults,” Bonds said. “I have no advice for you.”

The Giants think Bonds’ week as a hitting instructor will be a big help on the field. Bonds floated the idea of a reunion at an offseason charity luncheon, and the Giants — from Bochy to team President and CEO Larry Baer — felt the time had come for baseball’s all-time home-run hitter to return home.

“We have a great mind here that I know has so much to offer to us,” Bochy said. “We’re all going to enjoy this week and use his knowledge.”

The Giants have a rotating cast of former players come through camp annually. On a perfect Scottsdale day, Bonds was listed as a roving instructor, alongside former teammate Rich Aurilia. Bonds said he isn’t sure if he will even be good at coaching, but he wasted little time trying to find out. Wearing his new pants and a light Giants jacket, Bonds planted himself behind the main batting cage at Scottsdale Stadium, talking swing mechanics with Michael Morse and Angel Pagan and then discussing balance with fellow MVP Buster Posey.

Mostly, Bonds seemed to be enjoying himself. The smile was painted on, a far cry from the scowl that became so familiar late in a 22-year career.

“I needed that guy to play. I needed him,” Bonds said. “It was who I was at the time, but it’s not who I am now on a day-to-day basis. I’m the same person, just a different character. I can still be crazy, but I’m a lot calmer. I’ve toned down a little bit.”

Bonds was introduced to the team before batting practice, and afterward he sat in the dugout for a 3-2 loss to the Chicago Cubs. It was similar to any other guest instructor’s day — if you looked past the half-dozen camera crews following Bonds’ every move, the crowd of national reporters in town for the first time all spring and the publicist often at Bonds’ side.

As he mimicked his famous swing during cage conversations, Bonds looked very much like a man who could still step into the box and rocket one into McCovey Cove. He hit 28 home runs in his final season and led the majors with a .480 on-base percentage, but no other teams called when the Giants decided that it was time for the daily circus to fold its tent.

Bonds said he isn’t sure if he was blackballed. He just knows he wasn’t pursued.

“Nobody ever called me up and asked, ‘What’s he like?’ ” said Peter Magowan, the former managing general partner who brought Bonds to San Francisco in 1992. “And I sure as hell didn’t call anybody up and say you ought to take this guy, he’ll probably hit 40 home runs for you. I had no communication with anybody.”

That left Bonds unsure if he would ever return to the organization. Years later, he comes back to a sport that has tried to cleanse itself, albeit with mixed results. One of the best left fielders in baseball, Milwaukee’s Ryan Braun, and the most prolific Giants left fielder since Bonds, Melky Cabrera, have been suspended for PED use in the past two seasons. But both are back in a lineup this spring, along with scores of others who have served their unpaid time away from the clubhouse.

In Washington, former teammate Matt Williams is the manager, despite being named in the Mitchell Report that detailed steroid use in baseball. In Los Angeles, McGwire serves as the Dodgers’ hitting coach, four years after publicly admitting that he used performance enhancers throughout his career.

Bonds broke McGwire’s home run record in 2001 and set the all-time mark of 762 in his final season. Many lesser sluggers have followed the same instructor path, but in this case, Bonds really does carry an asterisk, courtesy of the courts. Bonds slipped back into a familiar jersey as a felon. In September, a federal appeals court upheld a conviction for obstruction of justice, stemming back to a grand jury investigation into the BALCO drug lab. Bonds served a month of home confinement.

It’s no coincidence that his return to the Giants came only after he had put some of his legal issues in the past.

“The timing is better now for me,” Bonds said. “Back then, it just wasn’t right. Now the timing is just better. There’s a lot behind me now.”

For more on the Giants, see Alex Pavlovic’s Giants Extra blog at blogs.mercurynews.com/Giants. Follow him on Twitter at twitter.com/AlexPavlovic.