Nolan Arenado and Matt Chapman had Gold Glove starts at El Toro High in Lake Forest

The line drive off Troy Tulowitzki’s bat in July seemed destined for left field until Matt Chapman, the rookie third baseman for the Oakland Athletics, intervened.

Chapman sprawled to his left to make a diving stop, landing chest-first on the turf in Toronto. He rolled over and, from one knee, fired to second baseman Jed Lowrie to start a double play.

It was one of several dazzling plays in a 3 ½-month debut season that had many comparing Chapman to Colorado third baseman Nolan Arenado, the five-time Gold Glove Award winner and gold standard for the position.

“As far as hands, feet and arm strength, he’s one of the best third basemen I’ve ever seen,” Lowrie said of Chapman. “He’s able to make plays most people can’t. He does something every night that seems to make you say, ‘Wow.’ ”

A certain high school coach in South Orange County will have a similar reaction if Chapman and Arenado win Gold Gloves in the same year.

Arenado was a senior shortstop and one of the nation’s top prospects at El Toro High in Lake Forest in 2009. His backup on that team, an undersized sophomore who only played shortstop when Arenado pitched, was Chapman.

“One high school producing the Gold Glove third baseman in each league in the same year? I don’t think that’s ever happened,” said Mike Gonzales, in his 18th season as coach at El Toro. “It would be a great marketing tool for our program, wouldn’t it?”

Gonzales might want to start on that brochure. Chapman’s path to the award eased this season with the trade of 2017 American League winner Evan Longoria from Tampa Bay to San Francisco and two-time winner Manny Machado’s move from third base to shortstop.

Had Chapman not been limited to 84 games in 2017, he might have won as a rookie. Among third basemen who played 700 innings or more, Chapman ranked second behind Washington’s Anthony Rendon with a 10.4 overall defensive rating, according to Fangraphs. Arenado (9.0) was third.

The 6-foot, 210-pound Chapman had 19 defensive runs saved, second most in baseball. Arenado saved 20 runs in twice as many innings (1,343). Chapman’s 9.2 ultimate zone rating was second behind Rendon.

Chapman is not immune to errors. He made 13 last season, and his wide, one-hop throw to first in the seventh inning Friday night allowed the Angels to score two of their five unearned runs in a 13-9 comeback win over the A’s.

But even with that error — his first of the season — Chapman entered Saturday’s game with a 2.3 defensive rating, best among big league third basemen.

“That’s something I aspire to and something I feel I’m good enough to do,” said Chapman, speaking before Friday’s game, of earning the Gold Glove. “It would be cool for Nolan and I and our coach. The NL one seems pretty locked up.”

Though they were teammates at El Toro, Chapman and Arenado were not on equal footing there.

Arenado, who turns 27 on April 16, was a second-round pick who made a beeline from high school to the big leagues, reaching Colorado in 2013 and establishing himself as a perennial All-Star and most-valuable-player contender.

“I always knew he was gonna play in the major leagues,” Chapman said. “Did I know he’d win five straight Gold Gloves and three Silver Sluggers right off the bat? No. But I saw him play every day, and he was really good.”

Chapman, who turns 25 on April 28, did not take a direct flight to Oakland. He was 5-foot-5 and 125 pounds as a high school sophomore, with great skills, a nice feel for the game and … no position.

“I sat the bench while he played,” Chapman said of Arenado. “If guys threw their helmets and got into trouble, I got to come in.”

Chapman started as a junior and senior but was not drafted out of high school. It took a growth spurt and three years at Cal State Fullerton, where he added muscle to his frame and power to his game, for Chapman to develop into a first-round pick in 2014. He reached the big leagues June 15.

“He was young, and he was always willing to work, but he was just really small,” Arenado said before a Rockies game in San Diego last week. “He’s big now. He always had tools. You could tell he had potential to be really good, and now he’s turned himself into a really good ballplayer. He was a late bloomer.”

Chapman was Arenado’s understudy in 2009. He took ground balls with Arenado every day and tried to emulate his fielding style, throwing motion and work habits.

“Matt was like a sponge,” Gonzales said. “He looked up to Nolan and ate up everything he could.”

The elder shortstop clearly rubbed off on the younger one.

“I learned a lot just from watching him work, how he went about his business,” Chapman said. “It was ingrained in me that if you want to achieve something, it’s through hard work.”

Arenado sensed Chapman’s constant gaze but never felt smothered.

“He was never a pest,” Arenado said. “As an underclassman, he was a good one. He didn’t have a big mouth. He knew his place. There were some other freshmen and sophomores who were a little more talkative. He wasn’t that guy.”

Chapman is not as dangerous with the bat as Arenado, who averaged 40 homers and 131 RBIs from 2015-2017. Chapman hit .234 with 14 homers and 40 RBIs as a rookie.

But he’s off to a fast start this season, entering Saturday with a .412 average, three homers — including a three-run shot off shot off Shohei Ohtani on Sunday and a two-run shot Friday off Cam Bedrosian — and seven RBIs.

“I want to be more consistent and maybe take a page out of Nolan’s book and come through more in RBI situations,” Chapman said. “That’s something I can work on.”

Chapman and Arenado have faced each other in spring training. They will square off in the regular season for the first time July 27-29, when the A’s play at Colorado.

The two have appeared on the same highlight shows, creating goose-bump moments — and a few flashbacks — for their old coach.

The left side of the El Toro infield is where ground balls went to die in 2009. Slow rollers up the middle were charged and scooped. Shots to the hole were gloved with backhand stabs. Throws to first base were firm and accurate, no matter the arm angle.

“I was fortunate enough to see the plays Nolan and Matt make now on a daily basis in high school,” Gonzales said. “If they got their glove on it, it was an out.”

Gonzales hopes to be in Colorado in July for the A’s-Rockies series.

“It’s so surreal to know those guys when they were kids playing Little League and high school baseball,” Gonzales said. “And then you see them in the big leagues and how mature they are, the fanfare they get, people wanting their autographs … it’s crazy.”

mike.digiovanna@latimes.com

@MikeDiGiovanna