The world No 39 admits he was in “a bit of a slump” and prepared for the PGA Championship at Bethpage Black by finishing in a tie for 29th at last week’s AT&T Byron Nelson.
Spieth is without a victory since The Open in 2017, when he was world No 2, but despite going without a top-20 finish this season believes he is not far from challenging for titles – if he can improve his driving.
Asked what has eluded him in his game, Spieth said: “It’s just been my driving of the golf ball.
“Even on some of the good rounds I get away with a bad couple of drives, but then over the course of four rounds, you just can’t continue to get away with them.
“I feel like I’m working on one swing feel now instead of changing it up each round, which allows me to be more consistent, to recognise where the club face is and be able to time it a little bit better.
“And that’s only been the last week or so that I’ve been really sticking to kind of one swing feel, really nailing it down. But it’s just been the driving.”
Spieth says he made a “dumb decision” in the final round of last week’s PGA Tour event to incorporate a couple of new shots into his game, as he closed with a level-par 71 to finish 12 shots behind champion Sung Kang at Trinity Forest Golf Club.
“I think it’s been an adjustment being in a bit of a slump,” he added.
“It actually may have even been harder on Cameron (McCormick, his coach) than it has been on me because of the physical side often being me trying to tell him, ‘hey, that doesn’t feel right, even though that looks right to you.
“I think we’ve both had to block out a little bit of outside noise from experts that may not actually know what’s going on.
“I don’t want to use the word negativity but the questioning and the wording that’s used to describe me by media, or whatever, over the past year has only come up because of the amount of success that I’ve had.”
The 25-year-old will join Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods in winning a career Grand Slam if he can overcome his technical struggles to lift the Wanamaker Trophy this week.
“I think I’d be the sixth person which would be a pretty unique fraternity to be in,” Spieth said. “That would be a dream come true for me.
“But I also recognise that if I continue to stay healthy and play, I’ll have, I don’t know, 30 chances at it. One of them is bound to go my way, right?
“It’s about staying in the moment for me for every PGA Championship, just as it is at every major.
“I feel like I’m more patient in majors with letting courses come to me than I am at other tournaments, and I feel like this is a good time for me to test that out.”
Spieth’s best finish this season was a tie for 21st at the Masters in April and the American says the outside pressure he is facing is testament to the success he enjoyed early in his professional career.
Asked what it would mean to join golf’s most exclusive club, Spieth added: “I think the four majors provide four different tests of golf, so it tells you your game travels anywhere and you can win the biggest events on any type of course in any situation.
“Each major championship has its own identity, so you’ve mastered golf, is kind of an easy way to say it, if you’re able to complete a career grand slam.”