SEATTLE -- While many of the Mariners' top prospects are still waiting in the wings, J.P. Crawford made his arrival in May, and the club now has a better idea of the strengths and weaknesses of its shortstop of the future.

Crawford’s first season with Seattle proved to be a positive, as he immediately solidified a shaky infield defense and displayed a potent bat with a torrid June, but also left plenty of room for improvement as he struggled at the plate in the second half and was sent home for the offseason with instructions to get physically stronger and better prepared to withstand the rigors of a 162-game season.

At 24, Crawford fits nicely into the Mariners’ plans of molding a contending team around its young nucleus. The California native was a top prospect himself coming up in the Phillies’ system, a 2013 first-round Draft pick whose star faded a bit when he was thrust into Philadelphia’s Opening Day lineup at shortstop in '18 and wound up battling through an injury-plagued season before being traded to Seattle in the Jean Segura deal.

The Mariners felt they bought low on Crawford and foresee a bright future for the 6-foot-2, 199-pounder, who has four more years of team control before hitting free agency.

“I definitely learned a lot,” Crawford said as he wrapped up his first year in Seattle. “Finally getting a chance to play every day at the Major League level, I got my feet wet a little and got comfortable out there. I feel like I belong and still have a lot to prove. I still have to go out and work hard every day and prove I can be out there every day. But I think overall, this year went really well.”

What went right?

Crawford hooked up with veteran infield coach Perry Hill even before Spring Training started and latched onto Hill’s energetic approach and focus on footwork fundamentals, which proved to be huge in helping him iron out the throwing errors that plagued his brief tenure with the Phillies. 

While Crawford’s offense slumped in the second half, his glovework reassured the Mariners -- as well as Crawford -- that they’re on the right track.

“I go out there with confidence, knowing I can make any play,” Crawford said. “Just making the routine plays, now it’s night and day for me thanks to Perry. Going out there feeling comfortable, that’s what transforms you into a good player. I knew I had a lot of work to do last offseason, with my footwork and just getting my body lined up to the bases and all that good stuff. Thankfully we got Perry and thankfully I met him. He changed my career.”

What went wrong?

Crawford came out swinging when he was promoted to the Mariners in mid-May, posting a .310/.380/.500 line with three homers and 22 RBIs in his first 33 games, even while missing two weeks with a sprained left ankle.

But as the season wore on, the youngster wore down at the plate and he hit just .178/.275/.297 with four homers and 24 RBIs over his final 60 games.

“Though J.P. has had the opportunity to play in the big leagues before, he's never really played a six-month season,” said Mariners general manager Jerry Dipoto. “Playing every day at this level can really wear you down. We saw that with [Daniel Vogelbach] as well. It's their first chance of doing this and it’s a huge experience. It's very valuable for them. They'll go home in the offseason and my guess is they’ll be better for it.

Best moment

Crawford supplied walk-off hits to beat the Tigers on July 28 and the A’s on Sept. 27, and he also notched a career-best four hits -- including a home run -- and four RBIs in a June 23 win over the Orioles. But the one unforgettable moment for the youngster?

That would have to be the spectacular defensive play he made for the final out in the top of the ninth inning against the Tigers on July 26, with a diving stop and twisting, off-balance throw to nail Jeimer Cadelario and set up a walkoff, 3-2 win in the bottom of the frame.

“Mercy,” said Hill, 67. “That was one of the best plays I’ve seen, and I’ve been around awhile.”

2020 Outlook

The Mariners opened this past season with veteran Tim Beckham at shortstop for the first six weeks, but it’ll be Crawford’s job from Day 1 next spring. He’ll anchor an infield that could also include youngster Shed Long at second base as the club continues shifting into its youth movement.

Crawford doesn’t turn 25 until January, but the Mariners like his on-field leadership and feel he’s primed to be part of their core group going forward. They’d love to see him take the next step offensively as his speed and power combination are intriguing, but defense figures to remain the top priority.

“I'm thrilled with where J.P. is at and I think he's going to be a staple here,” Dipoto said. “He's our shortstop moving ahead, and we love the development he made, especially on the defensive side. He took huge strides.”