Clayton Kershaw is turning 30, but he doesn’t feel that old

No competitor, in any sport, is more focused than Clayton Kershaw. On the days he pitches, there is no tolerance for distraction.

But this is spring training, where the atmosphere is lighter and the crowd sits extra close to the field. On Sunday, as Kershaw adjusted his batting glove in the on-deck circle, a group of fans serenaded him with a chorus of “Happy Birthday.”

Kershaw turned for a moment, tipping the brim of his helmet to the impromptu choir. On Monday, the greatest pitcher of our generation turns 30.

“Thirty just sounds old,” Kershaw said. “I don’t feel old. But, especially with the group of guys we have in here, 30 is different. The core of our team is 25-ish.

“A wife and two kids, I start feeling old. And now I’m 30.”

His 20s were incredibly special: marriage, children, the construction of two homes for vulnerable children in Zambia, and community service in Los Angeles, his hometown of Dallas and the Dominican Republic.

And on the field: a World Series appearance, a most valuable player award, three Cy Young awards, seven All-Star appearances, and the lowest career earned-run average of any major league pitcher ever to throw 1,000 innings.

“It’s been a lot of fun,” Kershaw said. “I’m not a very reflective person, but I don’t take for granted the time. No doubt about it. Hopefully I get to do it for a little bit longer.”

Dodgers manager Dave Roberts would not go so far as to say Kershaw could maintain that unprecedented level of excellence well into his 30s. On the other hand, Roberts said, Kershaw thrives on the location and command of his pitches, not on an overwhelming fastball velocity that would be bound to decline in his second decade in the majors. His average fastball velocity last season, at 92.7 mph, did not rank among the top 50 pitchers with at least 100 innings.

“The dominance of what he’s done his entire career, that’s a big ask,” Roberts said. “But I still think he’s right there at the top of the game.”

Kershaw dominated the San Diego Padres on Sunday, throwing five shutout innings, striking out eight, and delivering the double that drove in the Dodgers’ lone run. His Cactus League earned-run average is 0.00, and yet he declined to declare himself unconditionally ready for the season.

“You never know,” he said. “I’ll let you know on opening day, I guess.”

Rotation alignment

Kershaw, Alex Wood, Kenta Maeda and Rich Hill will start the season-opening series against the San Francisco Giants, Roberts said.

Hyun-Jin Ryu will be the fifth starter. He’ll start the opener of the Dodgers’ first road series, against the Arizona Diamondbacks.

The Dodgers will start all left-handers in that series. The Diamondbacks last season had an OPS of .739 against left-handers and a league-leading OPS of .787 against right-handers.

Trayce trade?

The Dodgers are expected to make outfielder Trayce Thompson available in trade talks. Thompson is out of options, so the Dodgers could lose him on waivers if they try to send him to the minor leagues.

Thompson appears to rank behind Matt Kemp, Yasiel Puig, Chris Taylor, Enrique Hernandez, Andrew Toles, Joc Pederson and Alex Verdugo on the Dodgers’ outfield depth chart.

“I’m 27 years old,” Thompson said. “It’s time for me to get a shot in the big leagues.”

Thompson hit 13 home runs in the first half of the 2016 season, then missed the second half because of a back injury. He started last season 0 for 38, split between the Dodgers and triple-A Oklahoma City, and finished the lost season batting .122 in 27 games for the Dodgers and .212 in 95 games at Oklahoma City.

Thompson said his first choice would be to play alongside his Dodgers teammates.

“I love these guys,” he said. “They are my friends for life.”

Marathon man

Justin Turner was excused from camp Sunday so he could attend the Los Angeles Marathon. His foundation, one of the official charities of the marathon, sponsored a race team and raised more than $35,000 to help the less fortunate in Southern California.

“He wants to take his personal day to do stuff for the community,” Roberts said, “and I think that’s fantastic.”

bill.shaikin@latimes.com

Follow Bill Shaikin on Twitter @BillShaikin