SOUTHPORT, England (AP) — Jordan Spieth was four days shy of turning 24 when he delivered pure magic in the final hour at Royal Birkdale to win the British Open for the third leg of the Grand Slam. It was among the most astonishing finishes in a major championship.Perhaps even more astonishing? He has only two PGA Tour victories since. He has played in the final group at a major only once. What hasn’t changed is his optimism that he can get back to his best golf, now matter how far away that looks for a player who is No. 51 in the world, who has not been to the Tour Championship the past two years, who has not been in the conversation at a major in five years.“If you give up on reaching your ceiling, then I don’t see a point in playing anymore,” Spieth said Monday. “So for me it’s always about I’ll do everything I can to be trying to be at the very best in the world, because I know that I can be. I have been. It’s nice to have the blueprint.”The blueprint was nearly a decade ago — the pursuit of the calendar Grand Slam that ended with a bogey on the 17th hole at St. Andrews in 2015, his British Open title two years later, and playing in the final group at Carnoustie in 2018 as he tried to keep possession of the claret jug.