He was an artist and a scientist all at once, with confidence to match. And that worked at first, but as the days wore on and the losses mounted, the Mets needed a change. So on the same day that he dismissed manager Willie Randolph, Mets general manager Omar Minaya also cut ties with Peterson and first-base coach Tom Nieto.
"I certainly didn't sign with the Mets to be here," Warthen said. "I didn't think this was going to happen. My respect for Rick Peterson is above all. I don't think anybody works any harder, prepares any better, and Willie's the same way. I am surprised."
His experience fits the job description. Warthen has been a pitching coach for the Tigers, Padres and Mariners, and most recently filled the same role for Triple-A New Orleans. Then, late on Monday night, Minaya offered him a job to replace a close friend.
"We just needed to make a change," Minaya said. "I thought one move was not going to be enough."
Warthen first met Peterson in 1978, back when the two were Minor League teammates in the Pirates' system. They remained friends over the next three decades, while each forged a name for himself in the coaching community.
Peterson's name grew bigger during the first part of this decade, when he helped develop Oakland's "Big Three" of Tim Hudson, Mark Mulder and Barry Zito. That work, more than anything, earned him a job with the Mets -- where he remained until Tuesday.
And in New York, too, he earned praise. Combining some unorthodox techniques -- blind bullpen sessions, to name just one -- with an emphasis on psychology, Peterson helped Tom Glavine reinvent his style at the end of his career, and he helped John Maine transform from a middling prospect into a potential ace. But he struggled with other pitchers, remaining unable to solve Oliver Perez's puzzling inconsistency, and taking heat after reportedly proclaiming that he could "fix" Victor Zambrano in 10 minutes.
The Mets traded their top pitching prospect, Scott Kazmir, for Zambrano, and Peterson couldn't back up his boast.
So now, years after that trade, Peterson is gone. His methods have been replaced by those of Warthen, who claims he isn't as "meticulous" as his predecessor. Warthen believes in pitching to contact, in stretching out both starters and relievers and in embracing manager Jerry Manuel's philosophy of defining strict bullpen roles.
More importantly, the new kid in the clubhouse believes in hinging his success on those around him.
"There's a plethora of information among all the coaches here," Warthen said. "They've got a great deal of information for me, and I want to use it all. I learned that a long time ago."
Some philosophies will change among that group now that Randolph is gone, and others won't. Manuel promoted longtime friend Sandy Alomar to bench coach following Tuesday's round of dismissals, plugging Ken Oberkfell in as the new first-base coach and Luis Aguayo as the third-base coach. The ideas will surely flow.
"Sandy and I have been good friends for along time," Manuel said. "Where he is now in his career, he can sit next to me and kind of give me that wisdom and insight on the game that I can appreciate."
And that's just the idea.
Warthen, for one, has already gone to work, overseeing Maine's bullpen session on Tuesday -- "I love this guy's arm," he said -- and scheming of ways to improve his rotation. He wants to stretch out Maine and Mike Pelfrey even further, to use his relievers for more than an inning each and to encourage Martinez to keep working with Perez.
"I've heard that Pedro has been in his ear a little bit," Warthen said. "If that works, let's go. I don't have an ego that way."
Perez has the skill, Warthen said, if not the confidence. Same with Pelfrey. Same with Maine. Warthen believes that he can help all three of them.
"And with guys like Santana and Pedro," he said, "if they need a cup of coffee, I'm going to be there."