"We're getting to the point now where he can master what he's started," Peterson said the other day. "The best way to say it is he's got his Brown Belt right now, and we're going for the Black Belt."
After a rocky spring start, Perez has settled into the type of rhythm that Peterson has envisioned. After being hit hard for four runs in two innings in his debut against the Tigers, Perez came back to hold the Indians to two hits and a run in three innings in his next chance. In his most recent game, he rationed the Nationals to a run in four innings, permitting two hits and two walks. Manager Willie Randolph particularly liked the way he "attacked" the hitters.
Another challenge awaits Perez on Thursday night. The Red Sox provide the Mets' competition, and depending on which players make the long trip from Fort Myers to Port St. Lucie, this is likely to be the most formidible batting order Perez will face until the season begins.
Perez still has a lot to overcome. He pitched for much of last season as if he was not only beltless, but clueless. He had a 2-10 record and 6.63 ERA with the Pirates before being traded to the Mets. The 139 runners he allowed in 76 innings was disheartening.
The change of scenery didn't help much either -- at least initially. Perez lost three of his four decisions and produced a 6.38 ERA in seven starts with the Mets. But he awoke in the playoffs and gave the Mets hope he could be a factor in this season's starting rotation by winning one start and pitching effectively in the other.
"I feel positive," Perez said recently. "That's why I have to keep working."
Catcher Paul Lo Duca said Perez may well be at his best when the pressure is the greatest.
"I think he's a guy that when you need a lot, which he showed with us, he can perform," Lo Duca said. "I think there are guys who get more amped up in certain situations, get psyched up for the playoffs. It looks like he does."
Perez, 25, is trying to recapture the magic of his 2004 season for the Pirates, when he produced a 12-10 record and a 2.99 ERA and struck out 239 batters in 196 innings. But from that point until the Mets acquired him with Roberto Hernandez for Xavier Nady at the trading deadline last July, Perez lost 15 of 24 decisions in 35 starts. And word circulated around the National League that he had mysteriously lost velocity off his fastball.
He once threw in the 92-94 mph range fairly regularly, but more recently his fastball has been closer to 88 mph, occasionally touching the low 90s .
Perez acknowledged that his velocity has declined, and he has an explanation.
"I was worrying more about mechanics instead of just throwing the ball," he said. "I was thinking too much on the mound and putting too much pressure on myself. But a lot of pitchers don't throw too hard. They know how to locate the ball."
Peterson said Perez's velocity doesn't concern him nearly as much as his ability to control his pitches.
"I'm working with where he is right now," the pitching coach said. "He just needs so many repetitions to lock in his control. It's like a workout program. It sounds simple to do 400 situps, but it takes focus and consistency and effort every time out there to get it done."
Lo Duca sees subtle signs that Perez is getting it together on the mound.
"He's starting to learn to calm himself down," the catcher said. "A couple years ago, he would have gone out there and tried to throw 100 mph and been all over the place. Now, he's working on throwing strikes. I'd rather have him give up runs by them hitting the ball than by walking guys."
Randolph repeatedly has said that the final determination on the rotation will be based on a full body of performance in exhibition games. He has resisted the urge to get excited or discouraged about any pitcher in camp. And that applies to Perez, too.
"When he's in a nice little rhythm, he has nasty stuff," Randolph said. "He has some of the best stuff we have in camp, from the left side, anyway. I like him."
Peterson gradually has brought Perez back to respectability by following a "process" in Spring Training. He wanted Perez to "pound the strike zone" with his fastball in his first outing, convinced that is the core pitch for most pitchers. Once Perez had a good feel with it, he branched out more with his breaking pitches in subsequent starts.
Perez remains somewhat baffled by what he has experienced in recent seasons.
"I don't know what happened last year and two years ago," he said. "But I want to learn and keep working."
It is that willingness to commit to a plan that has Peterson believing the worst could be in the rearview mirror.
Charlie Nobles is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.