SAN DIEGO -- Jose Castillo's first two trips to the Petco Park mound offer the two best examples of his unflappable demeanor.
A year and a half ago, during the World Baseball Classic at Petco Park, Castillo faced the heart of the USA lineup while pitching for Team Venezuela. At 21, and having never pitched above Class A Advanced, Castillo struck out Christian Yelich, then Nolan Arenado.
A year later, after his June callup, Castillo faced the heart of the Reds' lineup in his big league debut. He struck out the side -- Joey Votto, Eugenio Suarez and Adam Duvall.
"I like to pitch under pressure," Castillo said. "It makes me feel like I have to execute that pitch in that moment, and I like that."
"I love the look in the eye," said Padres manager Andy Green. "... You can tell he lives for that, savors that, wants that. There's just something in certain competitors where you can feel it, and they feed off big situations. He appears to be that guy, and he's been that guy from the second he showed up."
Castillo's poise -- and his filthy fastball/slider mix -- have some in the organization wondering whether he's future closer material.
Since his arrival, Castillo has been nothing short of brilliant. He's posted a 2.45 ERA entering play Friday night, and he's allowed 16 hits in 33 innings while striking out opponents at a 35 percent clip.
"The scary thing is he's still learning, still getting better," said pitching coach Darren Balsley. "He'll learn how to get hitters out, instead of just throwing the baseball with good stuff. He's smart. He has an intellect. He's a good self-evaluator. ... The sky's the limit with him."
Among the 426 pitchers who have thrown at least 500 pitches this season, Castillo ranks 32nd in swinging-strike rate (15.8 percent) and 30th in average exit velocity (84.8 mph). He's one of 11 pitchers in the top 10 percentiles of both categories -- joining established stars like Jacob deGrom, Chris Sale and Dellin Betances.
The secret to Castillo's success is twofold: He's hard to hit. And when he gets hit, he doesn't get hit hard.
"That's a good combination to have," Balsley said.
Castillo came to the Padres in the blockbuster three-team, 11-player trade that sent Trea Turner to Washington and William Myers to San Diego in 2014. With so many moving pieces, Castillo was an afterthought at the time.
That's no longer the case. In the last three weeks, Castillo has pitched 9 2/3 innings. He's allowed two hits and two walks while striking out 13. In some ways, his emergence could prompt a re-evaluation of that trade -- one of San Diego's most heavily scrutinized deals in recent memory.
That'll hold particularly true should Castillo develop into a lock-down closer.
"Absolutely, no doubt he could be," Balsley said.
"I wouldn't limit any possibilities with him," added Green.
Richard returns
Veteran left-hander Clayton Richard re-joined the Padres on Friday after undergoing season-ending left knee debridement surgery last week. He's expected to undergo an operation to clean up bone spurs in his right knee next month as well.
Richard's 2018 season came unraveled during the second half, and he finished with a 5.33 ERA in 27 starts. He refused to use his balky knees as an excuse.
"Here in the next couple weeks, I'll really take some time to self-evaluate and look at what needs to improve," Richard said. "Clearly there are things that need to be adjusted to be effective, moving forward."
Richard has one year remaining on his contract, and he's expected to join a wide-open race for rotation places next spring. If he misses out, he could have a spot as a long reliever out of the 'pen as well.
"I'll prepare to be a starter and do everything I can to win a spot," Richard said. "But there will be a lot of guys going for five spots. It's not going to be something I'm going to overly concern myself with. To get better, to get healthy -- that's my first focus."
Noteworthy
• The Padres have formally shut down Christian Villanueva's attempt to come back this season. The rookie third baseman sustained a broken middle finger in his right hand in August, and his return was always doubtful.
Villanueva batted .236/.299/.450 with 20 homers in 110 games this season.
• The Padres want to test their three rookie starters -- Eric Lauer, Joey Lucchesi and Jacob Nix -- in as many playoff-like environments as possible. They've already flipped Lauer and Robbie Erlin in the rotation, so that Lauer could pitch Sept. 21 in Los Angeles with the Dodgers in the midst of a pennant race.
They're expecting to do the same with Lucchesi, moving his start ahead by one day, so he pitches the final game of that series against the Dodgers. (Bryan Mitchell would be pushed to the following day.) That leaves Lauer, Nix and Lucchesi -- in that order -- to face the Dodgers Sept. 21-23.
• Rod Barajas, manager of San Diego's Triple-A affiliate in El Paso, joined the Padres on Friday, and he'll assist the coaching staff over the next week.