But don't call him a kid -- or tease him about his age.
He's been around. He knows the ropes.
Lyles made his debut on May 31, 2011, at 20 years and 224 days.
Now, more than 14 months later, he is almost a grizzled veteran.
"Last year, maybe my age was a big thing," Lyles said. "Not anymore."
Lyles has matured both on and off the field since a nifty seven-inning, two-earned-run debut against the Cubs at Wrigley Field. He carries a 2-10 record with a 5.70 ERA into his next start Friday against the Mets in New York. Earlier this month, he turned in the best back-to-back performances of his career, a pair of two-earned-run, seven-inning efforts against Washington (Aug. 7) and Milwaukee (Aug. 12) -- both at home.
The Hartsville, S.C., native slipped a little bit in his last outing, giving up five earned runs in four innings of a 12-4 loss to Arizona on Saturday.
"My confidence is still up," Lyles said. "My mind is set on finishing strong this season."
So far this year, Lyles has been plagued by rough one-inning stretches. He gave up six runs in the fifth inning of a 13-4 loss in Milwaukee on Aug. 1. He surrendered seven runs in the sixth inning of an 8-2 setback in Arizona on July 22.
"If you put my whole season in a short sentence, it would be the big inning," he said. "I've got to stay away from that and do a better job of minimizing my mistakes. Once my back is against the wall, I've got to get out of that inning with one or two runs instead of five or six, which is what I've been doing."
Lyles, selected in the supplemental round in the 2008 First-Year Player Draft, compiled a 2-8 mark with a 5.36 ERA last season as a 20-year-old.
Interim manager Tony DeFrancesco feels Lyles is ready to turn the corner.
"His velocity for me is up, his breaking ball is a little better, he's just going to have to learn how to command his pitches," DeFrancesco said. "He's definitely going to be a [successful] pitcher in the Major Leagues."