The American began the final day with a share of the lead but had to settle for a tie for ninth place on four under, four strokes behind winner Francesco Molinari, after shooting 76.
The 24-year-old said: “I’m fine. When you put yourself in position it goes your way sometimes, it doesn’t go your way sometimes.
“It was going to be a tough day. You knew you’d have three, four good looks at birdies, and the rest of the holes, you were just going to try to position it to make par.
“I played patiently, put good swings on it. I never got down on myself, I never got angry. I just didn’t make a putt today.
“But my stroke is there. It’s back, which feels awesome, and my game all together is back.
“So, I’m actually very pleased coming out of this week. Obviously, there’s the disappointment of not getting the job done today but I’m not going to win every single time.”
Spieth burst onto the world scene by winning the Masters and the US Open in 2015 and he narrowly missed out on a play-off at the Open in the same year.
With his form now returning after missing the cut at last month’s US Open, he feels he can get back to and better those levels of three years ago.
He said: “I believe that my best golf has yet to come, absolutely, even better than 2015.
“I believe that going through struggles, you start to realise where your tendencies are and how to compensate for it and turn them into advantages. I think that I have that going for me.”
Spieth admitted he was unsettled when he and playing partner Xander Schauffele were put on the clock as a warning over slow play.
He said: “I handled it OK, but looking back, that was a turning point in the round. I really rushed the 10th and 11th holes when we were being timed.”
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