PEORIA, Ariz. -- Luis Perdomo's sinker is such a new pitch, the rest of the baseball world is still learning about it.
Evidently, so is Perdomo.
The 23-year-old right-hander developed his signature out-pitch last May, when the Padres front office asked him to try something new. It helped turn Perdomo, then a struggling rookie reliever, into arguably the club's most effective starter.
But because it came about midseason, Perdomo says he's still learning to harness the pitch. With an offseason under his belt, he feels as though he'll be able to better command his biggest weapon this season.
"I'm still learning it," Perdomo said through a team interpreter. "I still have things to learn. It's just a matter of being able to control it, working to both sides of the plate and the corners and being able to manipulate it that way."
The downward movement on Perdomo's sinker is so natural that the Padres have asked him to stop "forcing it to sink," manager Andy Green said. They'd like him to be freer in his delivery.
After June 1 last year -- around when he began to throw the pitch consistently -- hitters averaged a 1.4-degree launch angle against Perdomo. Only Marcus Stroman's 0.7-degree angle was lower among pitchers with 200 batted balls against.

"He knows he's not a finished product," Green said. "He knows he's got a lot of learning ahead of him. ... [Last year] was a tremendous experience for him. He's just got to keep working."
Green seems certain Perdomo has the right makeup to do so. He pointed to a day during the offseason, when Perdomo spent over an hour talking with Padres prospects at the team's complex in the Dominican Republic. Green said Perdomo was very candid about "the fear he felt at the beginning of the year and the confidence he felt at the end of the year."
Now, it's on to Year 2 for Perdomo -- which means higher expectations and a more demanding workload. Perdomo, who has never cracked the 150-inning mark, could very well end up as the Padres' Opening Day starter.
"It's just about taking care of your body, keeping your weight up and making sure that you don't wear down," Perdomo said. "I'm really focused on that so I can sustain a larger workload over the course of a season."
News and notes
• Infielders Yangervis Solarte, Ryan Schimpf and Cory Spangenberg all will take reps at both second and third base this spring, Green said. Solarte figures to have a starting role locked up, but it's unclear where. He spent last season playing third, while Schimpf and Spangenberg served as second basemen primarily.
Meanwhile, infield prospect Carlos Asuaje, who had played some third base in the past, is "100 percent a second baseman" now, Green said. Asuaje is a candidate for a bench spot.
• Green didn't name a leader in the shortstop competition between Luis Sardinas and Erick Aybar, calling the race "an open competition." Both will take reps exclusively at short, while Rule 5 pick Allen Cordoba will also see time at second and third.