PORTRUSH, Northern Ireland -- During the final round of last month's U.S. Open, Jordan Spieth, long out of contention and coming off three consecutive bogeys, couldn't believe where his tee shot ended up on the 15th hole at Pebble Beach.

Spieth's ball was buried in the tall native grass on top of a deep fairway bunker. Spieth took off his hat, rubbed his thinning hair and drove an iron into the ground in frustration.

After waiting a few minutes for playing partner Sergio Garcia to hit his second shot from the fairway, Spieth became impatient and quickly whacked his ball out of the grass. Garcia turned and looked at him, apparently surprised that Spieth had hit out of turn.

Spieth salvaged par on the 15th hole, had birdie on 16 and then another bogey on 17.

After driving his tee shot into the thick rough on the right side of the 18th fairway, Spieth waited for the pair in front of him to clear the green. When they finally did, he drew back a hybrid, turned his hips and took an explosive swing at the ball.

It dribbled 75 yards down the fairway. He threw up his right arm and shook his head in disbelief.

The reinvention of Jordan Spieth -- or reclamation, depending on whom you believe -- continues this week at the 148th Open Championship at Royal Portrush.

There's no guarantee the next step won't be as ugly or frustrating as the past two, when Spieth finished tied for 65th at the U.S. Open and missed the cut at the Travelers the next week.

"Not anywhere near where I want it to be," Spieth said of his game last month, after shooting 73-69 at the Travelers, before taking a three-week break to prepare for The Open.

What once seemed so simple isn't anymore. The former World No. 1, who won so quickly and so frequently early in his career, hasn't claimed a victory in nearly two years, not since a three-shot win in the 2017 Open Championship at Royal Birkdale. That one, of course, is famous for his bogey from the practice range near the equipment trailers on the 13th hole of the final round.

"If not for my past success, I don't think I'd get as many questions about being in a little bit of a slump," Spieth said earlier this season. "I think people would look at me and say, 'He's coming along nicely.' But because of the success I've had, people don't look at it that way."

Spieth has had to answer questions about his lack of victories for much of the past two seasons. At the PGA Championship at Bethpage Black in May, Spieth corrected a reporter who suggested he's in a slump.

"Was," Spieth interjected.

The reporter then asked if others walked around Spieth on eggshells or were awkward around him because of his subpar play.

"No, I mean, I didn't, like, go away from the game for five years," Spieth said. "I just happened to not win in the last year and a half or so."

What was once endearing is now being closely examined, too. All of Spieth's tics -- constantly talking to himself, his ball and his caddie, Michael Greller; backing off shots; or reaching for a towel before every swing -- are scrutinized.

When Spieth and Greller came up with the wrong club selections on consecutive shots in the opening round of the U.S. Open, TV microphones captured Spieth's terse reaction.

"Two perfect shots there, Michael," Spieth told Greller. "You got me one in the water and one over the green."

Spieth was criticized on social media for throwing his caddie under the bus. After the round, Spieth explained that he was frustrated they hadn't come up with the correct yardage.

"I'm going to be frustrated that as a team we didn't figure out how to make sure that didn't happen," Spieth said. "Yeah, I may have looked like the bad guy there, but my intentions were that we should be in play if the ball is hit solidly, and I was out of play on both shots."

Of course, none of it probably matters if Spieth is winning like he did so often in the early stages of his career. He has won 11 times on the PGA Tour and had three major championship victories before age 24 (Tiger Woods had only two at that age).

Spieth became the youngest winner in PGA Tour history when he won the 2013 John Deere Classic at 19. He won five times in 2015, including the Masters (he was the second-youngest golfer to win a green jacket, behind Woods), U.S. Open (he was the youngest champion since Bobby Jones in 1923) and Tour Championship. He won twice more in 2016 and three more times in 2017.

His game has often been in disarray ever since. He is ranked No. 38 in the world.

"Your expectations are what drives your mentality, and when he came out and had so much success, his expectations went through the roof," said Kevin Kisner, who played two practice rounds with Spieth at Pebble Beach before the U.S. Open. "His mentality when he tees it up on Thursday -- and it's this way with any of us, not just him -- you expect to have a chance to win. This game can be a harsh reality when things aren't working."

According to Kisner, Spieth was working on two swing changes before the U.S. Open. It's a continuation of what has seemed like a never-ending process as Spieth tries to regain form. Spieth even admitted during the 2018 PGA Championship at Bellerive that he'd been working on the wrong thing in his swing for months and needed additional time to make corrections.

"The things I've been working on are so drastic that it's just really difficult to try and play through it, I guess," Spieth said.

Cameron McCormick, Spieth's swing coach, did not respond to an interview request from ESPN.com.

Spieth isn't the first PGA Tour player to alter his swing. During the mid-1980s, Nick Faldo decided to change his swing, which he believed was unreliable and involved too much wrist. Under the guidance of coach David Leadbetter, Faldo's swing became more compact and efficient. The changes helped Faldo win six major championships from 1987 to 1996.

Like Faldo, Curtis Strange redesigned his swing from a powerful but erratic action to a more compact and tighter swing. After the face-lift, Strange won back-to-back U.S. Open titles in 1988-89.

"Sometimes it doesn't work out, but you've got have the patience to do it if it's going to be a long-term change and you're really committed to it," Strange said. "You've got to have commitment and patience because there's going to be a rocky road ahead of you, especially when you're doing it during tournament play. Then you finally get to a point where you're really practicing well, but now you've got to believe in it. Can you hit that shot to a corner pin when there's pressure on? It's tough."

Even Woods, who has won 15 major championships, has made dramatic changes to his swing at least three times.

Woods, after winning his first major at the 1997 Masters by a staggering 12 strokes with the lowest 72-hole total in history, completely overhauled his swing and started from scratch with the help of Butch Harmon.

After making the changes, Woods won once in 1998 and didn't win again for for more than nine months. Once he perfected the new swing, he won eight times in 1999 and nine times in 2000, including four majors in the two seasons combined.

"I was in it to find the answer to one question: How good can I be?" Woods said in the biography, Tiger Woods, by Armen Keteyian and Jeff Benedict. "I suppose I was searching for perfection, although that's not attainable in golf except for short stretches. I wanted to take control of my swing, and, hence the ball."

Despite his early success, Spieth was never considered one of golf's great ball strikers. During the 2015 season, he ranked 78th in driving distance (291.8 yards) and 80th in driving accuracy (62.9 percent of fairways hit). His greatest strengths were putting, chipping and his imagination around the green.

"The guy just gets the ball in the hole," said swing coach John Tillery. "He's one of the best scorers in history. When you're that good, it's easy to never feel like you're that far off."

In reality, though, Spieth's short game masked flaws in his swing.

"In my opinion, his stats from tee to green were never up to par with his record that he established early on," Strange said. "He was a great chipper and putter. I applaud him for trying to get better. But in the long run, you're trying to be a better ball striker. I hope he can accomplish that. He's certainly accomplished a lot with what he has."

Given how much Spieth won early in his career, and how much he has struggled lately, it might be fair to ask if his best golf is in his rearview mirror. Was his 2015 season, which was as good as many players' careers, as good as it gets? Most players would be satisfied with what Spieth has accomplished.

Two-time U.S. Open champion Andy North, an ESPN golf analyst, doesn't think Spieth is too far away from returning to form. He points to Spieth's three consecutive top-10 finishes at the PGA Championship, Charles Schwab Challenge and the Memorial -- before the struggles at the U.S. Open and Travelers -- as an indication that there's light at the end of the tunnel.

"I think he's out of his funk," North said. "He's played some really good golf over the last month or two. If you'd look at any other guy with three top-10s in a row, you'd say he's playing unbelievably. But because he's coming out of a slump, everybody wants to talk like he's still struggling because he hasn't won. To finish in the top 10 three weeks in a row, that doesn't happen very often. You can probably count how many times it happens in a year on one hand."

And Spieth was in contention in two majors last season: He shot 64 on Sunday at the Masters to finish two strokes behind Patrick Reed, and he tied for ninth at The Open Championship. He didn't have a birdie in the final round at Carnoustie, where he finished four shots back of Francesco Molinari.

"If you put yourself in position enough times, the bounces go your way, sometimes they don't," Spieth said. "I had a chance to win two majors last year feeling like I had a 'C' game. I mean, that's realistic. I was in the final group Sunday of last year's Open at Carnoustie, and I woke up saying, 'How in the world am I in the final group at Carnoustie?'

"And that's not just me not believing in myself -- that's just legitimately, mechanically, how I felt through my swings. It just wasn't good compared to when I was on."

Finding that form again hasn't been easy.

"He's come through the darkest part, and he's doing some really good things," North said. "I think he's gotten through the worst of it and figured some things out. ... Winning is hard. It's hard to do it. You go through stretches where you don't do it, and if you're putting pressure on yourself, then you're really going to have trouble with it. There's no way you can figure it out. I think it's something we all go through."