Trea Turner wants to play shortstop for as long as he can. And that means the work never ends.

Trea Turner has a bad habit.

As the Phillies shortstop explains it, he tends to read a hitter’s swing and move forward before gauging the quality of the contact. If the ball is hit too hard, he may not be in the optimal position to field it cleanly. Or he may be off balance, leading to a poor throw. Sometimes his athleticism enables him to overcome his technique. Sometimes, but not always.

Turner can’t say why or when he began doing this. Maybe it’s an innate shortcoming. Old habits die hard. But at least he’s aware of it now. And after leading the majors last season with 23 errors, the most by a Phillies shortstop since Desi Relaford’s 24 flubs in 1998, he worked diligently to correct it.

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At the end of spring training, Turner even thought he had it licked.

But then, in the fifth inning on opening day at Citizens Bank Park, the Braves’ Sean Murphy chopped a 95-mph grounder. Turner misread it, tried to overcorrect, took an inefficient path to the ball, and reached down just as it scooted under his glove and into left field.

Whoops.

“It was like, ‘Oh, man. That’s exactly what I’m trying to not do,’” Turner said before a game the other day. “I didn’t do it all of spring training and get in that first game, opening day, and I do it.”

Three weeks later, Turner appears to be making progress, anecdotally if not analytically.

Notwithstanding the opening-day miscue, the old-fashioned eye test indicates that he’s making the routine plays more consistently and the tougher ones more often. He’s more technically sound. He appears to be under control, with a sturdier foundation.

The defensive metrics aren’t as kind. Through Thursday, Turner ranked a smidge below average for shortstops in defensive runs saved (minus-2) and Statcast’s outs above average (minus-1), proving only that he still has work to do.

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But last season, Turner ranked 30th among 35 qualified shortstops in outs above average (minus-5) and second-to-last in defensive runs saved (minus-12). If not for the depth of his struggles at the plate — the former batting champ and two-time hit king was slashing .235/.290/.368 on Aug. 3 — his defensive regression would’ve gotten more attention.

So, sure, 2023 is a low bar. But the improvement is notable.

“Tremendous difference,” Phillies infield coach Bobby Dickerson said. “His balance is better. His [internal] clock is better. His ability to find hops is better. He’s gotten a couple mistakes that I thought he shouldn’t have made. He’ll admit that. But it’s just 100 times better.”

Is it good enough, though, for Turner, who will be 31 at the end of June, to stay at shortstop into his mid-30s, when most players age out of the position?

Say this for Turner: A decade after his major-league debut, he hasn’t lost a step.

Turner’s average sprint speed — 30.3 feet per second, as measured by Statcast — is nearly identical to his 30.6 mark as a rookie in 2015 with the Nationals. It’s also second in the majors so far this season behind Cardinals rookie center fielder Victor Scott II (30.4).

“That’s kind of how I base a lot of things, how I run, and I feel like my sprint speed’s at the top of the game,” Turner said. “And I’m seven or eight years older than a lot of the kids doing that.”

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Indeed, the sprint-speed leader board is a veritable kiddie pool, with Scott (23 years old), the Royals’ Bobby Witt Jr. (24), Phillies center fielder Johan Rojas (24), the Reds’ Elly De La Cruz (22), Rangers rookies Evan Carter (21) and Wyatt Langford (22), the Mariners’ Julio Rodríguez (23), and the Diamondbacks’ Corbin Carroll (23). After Turner, the next 30-something is Mike Trout, tied for 16th on the list through Thursday.

But Turner’s elite speed never translated into a Gold Glove. He could always lean on his athleticism to be at least an average defender at shortstop. In 2018, his defensive peak, he finished with 12 outs above average and eight runs saved.

Then came last season’s cliff dive. In describing his defense in his first year with the Phillies, Turner uses one word: “Brutal,” he said upon reporting for spring training.

“Last year was bad because of habits I had,” he said this week. “It’s about breaking those habits and doing things right, and then you go out and play and you have fun.”

But Turner’s diminished defense also renewed questions that came up during his free agency two winters ago. As interested teams, including the Phillies, weighed long-term contract offers, they studied how he may fit on a shortstop aging curve that is historically unforgiving.

Over the last 50 years, since 1973, 71 shortstops played in at least 100 games at the position in their age-31 seasons, according to Baseball-Reference.com. The group dwindles to 37 shortstops at age-32 and 34 at age-33.

Turner was surprised by the exclusivity of those clubs.

“When you mention that, I think back to a lot of the meetings I had with teams in free agency and talking about shortstop and defense,” he said. “I honestly felt like slowing things down would help me defensively. It’s not about first step or speed. It’s more like slowing things down and not being so out of control. I’m doing that now.”

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If anything, Turner said he realizes as he gets older that athleticism will get him only so far. Technique matters more. When he makes an error, he wants to understand why it happened and what he did incorrectly.

Turner takes that approach with his hitting. It’s why he believes he has maintained metronomic consistency at the plate for most his career until last season, when four months of extreme lows were followed by a scorching streak in August and September.

“I’m going to make mistakes, I’m going to strike out, whatever, but when I do them, I want to be able to fix them quickly,” Turner said. “Last year, I couldn’t fix things as fast as I wanted to fix them. In years past, if I struggled at the plate, I could fix that quicker. If I was struggling on defense, I could fix that quicker. Last year, for whatever reason, I just didn’t do that.”

It’ll help that he and Dickerson understand each other better.

Dickerson is highly esteemed as an infield coach. His catalog of Gold Glove mentees includes J.J. Hardy and Manny Machado with the Orioles. He helped turn Alec Bohm into a solid third baseman and taught Bryce Harper to play first base on the fly. Bryson Stott swears by him.

With Turner, the relationship took longer to build.

“I never knew him before, and he didn’t really know me,” Dickerson said. “When you’re a successful guy, you don’t want to just say, ‘Hey, tell me how to do this.’ There’s a time period of getting to know each other and trusting the information you’re getting.”

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Dickerson, 58, can be an acquired taste for some players. During infield practice, he hollers a mixture of encouragement and trash talk, slathering it all in a Mississippi drawl. He’s in your face, with a language all his own — “Dance with the ball!” — and finger-snaps to signal his approval. One Dickersonian drill involves a softball mask and tennis balls.

But Dickerson also knows when to back off. And he didn’t want to pile on last season while Turner was trapped in the worst hitting slump of his career.

“He was a ticking time bomb,” Dickerson said. “I don’t want to say it like that, but he was wound tight. He had a lot of pressure on himself.”

As the season went along, Turner asked Dickerson for more feedback. He received advice and had follow-up questions. Stott added input and helped build Turner’s trust in Dickerson.

Turner took many of Dickerson’s suggestions and implemented them in the offseason. Things began to make more sense. He felt better about how he transferred the ball from his glove to his hand. He was more comfortable with his footwork.

“And then he came to camp wide open, wanting to make some major adjustments,” Dickerson said, “which is very rare for a successful major-league player that signed for what he signed for. A lot of guys, you give them a contract, now they don’t give a [darn]. They’re paid. Sometimes he has too much give-a-[darn], I think.”

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A few nights ago, Turner caught himself lapsing into his old habit. He moved forward on a grounder hit by the Rockies’ Elehuris Montero. But rather than getting caught in a bad position and leaning back on his athleticism, he adjusted his feet and fielded the ball in a good position.

“There’s going to be some instances where I might not do something totally fundamental and I’ll make the play. That’ll happen,” Turner said. “But it’s about doing those fundamentals 90% of the time and being yourself and not thinking about it.

“Because I want to play short for as long as I can, but I also have to do it well. It’s not like I can just go out and stand there. I’m going to take pride in it, I’m going to work at it, and we’ll see where that goes. But I know I’ll put the work in for it.”