SEATTLE -- Throughout an MLB career full of tremendous highs and downright puzzling lows, Cardinals shortstop Paul DeJong has always had a knack for being a strong starter.

It’s the part after the strong starts that has tended to trip up DeJong in the past, but he is hoping he is immune to that happening now with a new-and-improved plate approach that certainly yielded stellar results on Sunday.

DeJong, now 29 with five years of MLB service time, homered in his first big league at-bat in Colorado back in 2017. The shortstop, who was demoted to Triple-A last year following two-plus seasons of hitting struggles, homered in his first game back with the Cardinals on July 30. On Sunday, in his first game back after spending much of the past month on rehab assignments because of an ailing back, DeJong homered again in a three-hit onslaught that sparked the Cardinals’ offense to a 7-3 win over the Mariners at T-Mobile Park.

“Maybe it’s just the excitement of being back,” DeJong said of his notable homer history in his first games back at the MLB level. “Being able to take it moment by moment and learn from [past experiences], I want to propel myself with that same attitude moving forward.”

DeJong, who had three hits, a home run and six RBIs in his final Triple-A rehab game before making the journey from Memphis to Seattle, helped the slumping Cardinals avoid being swept by the Mariners for the first time in franchise history. After St. Louis scored just six runs in the first two games of the series, DeJong was an integral part of an offense that pounded out 13 hits and smashed three home runs. Lars Nootbaar homered on the game’s first pitch, Nolan Gorman broke a 3-3 tie with a three-run smash and DeJong gave the Cardinals breathing room with his seventh-inning clout. DeJong hit singles in two of his first three at-bats, and his 408-foot shot left the bat at 102.9 mph, according to Statcast.

“Pauly looked good today, and that was a big homer for insurance there,” manager Oliver Marmol raved. “We’re encouraged [with DeJong’s progress]. This is a guy who put in a lot of work this offseason. We were excited to see it in spring, but unfortunately, we weren’t able to. We wanted to give him enough at-bats in that rehab stint to show what he was capable of doing, and today was a good start.”

Of course, the Cardinals and DeJong have been here before, hopeful the shortstop has rediscovered the swing that allowed him to hit 25, 19 and 30 homers in his first three MLB seasons. After appearing in the All-Star Game in 2019, DeJong’s career slowly slipped away over the next three years. Injuries and illness rattled him in '20, and his batting average plummeted to .197 in 2021 and .157 in ‘22.

Last season, DeJong was sent to Triple-A Memphis following another slow start, and he seemed to locate a trusted and repeatable stroke. He homered in that first game back with the Cards in Washington last July, but more struggles followed.

With the team demanding he make substantive changes at the plate, DeJong spent most of the winter at the Cardinals’ complex in Jupiter, Fla. What arose from that work was a more upright stance that features only a minimal stride to better help him be on time and balanced at the plate. He used that on Sunday while almost effortlessly ripping balls back through the middle of the field.

“I think it’s monumental, really,” said DeJong, who wore a maroon suit with a paisley pattern for the team’s flight to San Francisco, where the Cards will face the Giants over the next four nights. “I don’t really watch myself anymore [on video replays] because I want to be able to feel it out there. So I don’t really know what it looks like, but I know what it feels like in my head. I feel on time and ready to hit. Obviously, we have a long way to go, but today was a great start.”

Jack Flaherty, whose three runs allowed in six innings on Sunday gave the Cardinals the kind of quality start they badly needed, feels DeJong is finally poised to be a sustainable difference-maker for St. Louis.

“It was nice to see Pauly today, and I gave him a big hug,” said Flaherty, who allowed six or fewer hits for a 30th straight start since September of 2020 -- the longest active streak in MLB. “We know what Paul can do when he’s right. When he does what he can do, it adds another dimension to the lineup. We’ve got a lot of depth on this team."