The No. 1 player in golf already has three wins in 2015, including a World Golf Championship, and he has finished in the top 10 at both majors.

Halfway through the year, however, Rory McIlroy is playing second fiddle.

Remember the hype over McIlroy going for the career Grand Slam at the Masters? That was three months ago, and it seems like a lot longer. The attention has shifted to Jordan Spieth and his bid for an unprecedented sweep of the four majors in the same year. The real Grand Slam.

Arnold Palmer created it. Jack Nicklaus and Tiger Woods pursued it.

And now it falls to a 21-year-old Texan who just three years ago wasn't even a full PGA Tour member.

"We watch the elite athlete. We watch the mental focus and the preparation and the drive to become the best," Bubba Watson said. "That's where he's heading. Who knows if he'll ever become No. 1 in the world, but he's trending in that direction pretty quickly."

For a sport that gets criticized for its pace of play, the turnover is at warp speed.

Tiger Woods ended last year at No. 32 in the world, and he was excited about the direction he was going. He had a new swing consultant and a clean bill of health. He was 15 months removed from a five-win season in which he was voted PGA Tour player of the year for the 11th time.

And now it's a wonder anyone recognizes him.

Woods reached the halfway point of the year at No. 220 in the world. He has more rounds in the 80s (three) than the 60s (two). He has fallen so low in the world ranking that for the first time since he was a 20-year-old rookie in 1996, his appearance at The Greenbrier Classic contributes no points toward the strength of field.

Here are some of the highs and lows heading into the second half of the year:

BEST PLAYER: It's hard to argue against the Masters and U.S. Open champion. Spieth went wire-to-wire at Augusta National and tied the 72-hole scoring record set by Woods in 1997. He went birdie-double bogey-birdie at Chambers Bay and won only after Dustin Johnson three-putted from 12 feet. Only five other players dating to 1934 have won the first two majors of the year.

Overlooked is his victory in the Valspar Championship. Spieth got up-and-down for par from a nasty lie on the side of the hill at the 17th, and he got up-and-down from 35 yards on the 18th hole just to get into a playoff. He won on the third extra hole with a 30-foot birdie putt.

Does he have a chance at the Grand Slam? History says no. That short game says maybe.

ON THE RISE: Dustin Johnson has won every season since he joined the PGA Tour, so he never really fell very far. Even so, coming off that mysterious six-month break, golf's most athletic figure seems determined to reach his full potential. He won at Doral on perhaps the toughest course this year that had grass on the greens. He lost in a playoff at Riviera and was a 4-foot birdie putt away from a playoff against Spieth at Chambers Bay.

If he can put the U.S. Open behind him — Johnson has a short memory — he could be a major threat the rest of the year.

SLIDING: At the peak of his game, there were two tours — the Tiger Tour and the PGA Tour. The same applies now.

In the non-Tiger division, this might be a toss-up between Ryder Cup partners Graeme McDowell and Victor Dubuisson. McDowell spoke of his lack of motivation as he adjusts to life with a new daughter. He hasn't finished in the top 25 since January. In his last 10 starts, Dubuisson has missed half his cuts and has not finished better than 20th.

For the second half of the season, keep an eye on Martin Kaymer. He is winless since his U.S. Open title last year and has missed the cut six times in his last nine events.

CLASS OF '11: That would be the high school graduating class of Spieth, Justin Thomas, Daniel Berger, Patrick Rodgers and Ollie Schniederjans. Thomas played in the final group on the week three times during the West Coast swing. Berger lost in a playoff at the Honda Classic. Rodgers won on the Web.com Tour, challenged McIlroy at Quail Hollow and now has partial PGA Tour membership. Schniederjans, No. 1 in the amateur world ranking last year, will turn pro after the British Open.

Four of them — Rodgers was not there — played a practice round at Innisbrook in March. They began asking who was the youngest. It was Spieth.

BEST FINISH: Rickie Fowler went eagle-birdie-birdie to get into a three-man playoff at The Players Championship. He played the island-green three times on Sunday and took a total of six strokes.

BEST SHOT: Spieth's flop shot off a tight lie above the 18th green in the third round at the Masters. It turned bogey at best into a par and gave him a four-shot lead going into the final round.