Truth is, the hard work is just beginning.
'It starts my stretch now through the U.S. Open, and what a great place to start,' Mickelson said.
But after three weeks off, Lefty has his eyes on Winged Foot three weeks away.
'I thought that New Orleans was a very emotional week, seeing the city and being there. And it took a little more out of me, and I was just tired,' Mickelson said. 'Now I'm excited to get back out and play. I have the energy and the motivation to go work hard and practice. It was tough there for a week or two. And now after a nice, little relaxing break, I'm ready to get back at it.'
Mickelson spent much of the holiday weekend at Winged Foot before coming to Muirfield Village, where so much has changed since the last time he was at the Memorial.
It's the first time Mickelson has as many majors as any other player in the field.
For one thing, he didn't have any majors in 2002, and now has won three of the last eight. Of more significance, this is the first time tournament host Jack Nicklaus (18 majors) is not playing, and the first time Tiger Woods (10 majors) has skipped the Memorial since he turned pro. Woods hasn't played since his father, Earl, died May 3.
The other big change is the bunkers, which are getting far more attention than the weather.
Nicklaus suggested -- and the PGA TOUR concurred -- that he would use specially designed rakes that create furrows in the sand, turning bunkers into true hazards. It will be harder to get spin on the ball, meaning players will have a tougher time saving par from around the green, or getting near the green when they're in a fairway bunker.
'It's certainly the easiest way to make the golf course harder, to change the rakes,' David Howell said. 'It's the cheapest way.'
One thing that hasn't changed is the quality of the course and the field.
Even without Woods, a three-time winner at the Memorial, the tournament has eight of the top 10 players in the world ranking. The other absentee is David Toms.
Mickelson attributes his absence the last four years to scheduling, and one thing that helped was moving the pro-am back to Wednesday. The tour has a policy that players must participate in the pro-am to tee it up in the tournament, and Mickelson was busy last year practicing at Pinehurst No. 2 for the U.S. Open.
'I've been trying to come back, and I loved playing here,' Mickelson said. 'In between the Masters and the U.S. Open, there are eight really good tournaments, and this has just been the one that has fallen out the last couple of years.'
Mickelson has never played particularly well at Muirfield Village. He tied for ninth the last time he was here, which was the first time he had finished inside the top 10. And the bunkers won't make it any easier.
Lefty wasn't sure what to make of them, but he did draw one conclusion.
'I don't mind making a bunker a hazard, because that's what it is,' he said.
The Memorial also features Kevin Hall, the first deaf player on the PGA TOUR. He has missed the cut in his four previous starts when he received sponsor's exemption, but the former Big 10 champion from Ohio State believes he's ready to stick around all four days.
Jay Haas can tie a record by making the cut.
The 52-year-old Haas, coming off a victory in the Senior PGA Championship for his third consecutive Champions Tour trophy, can tie Tom Kite for making the most cuts -- 590 -- in his career. This would be a good place for that to happen, as Haas has made the cut 26 times in his 28 starts at the Memorial.
A couple of other players would like to end long droughts. Vijay Singh hasn't won on the PGA TOUR since August, a stretch of 20 tournaments. Ernie Els hasn't won on the PGA TOUR since two years ago at the Memorial, although he believes his game -- and recovery from surgery on his right knee -- is starting to come together.
Even so, most of the attention is on Mickelson and how he will play these next two weeks before the U.S. Open.
Despite not having played at Muirfield Village for four years, he remembers enough of the course to notice the slight changes Nicklaus has made -- No. 1 is 21 yards longer, a tree was removed on the 10th, the par-3 12th hole over water is about 10 yards longer.
As for Winged Foot? Mickelson now is all too familiar.
'Winged Foot is such a good course that it won't require ridiculous things to keep par a good score,' he said. 'Looking at it now, I don't see how guys are going to shoot under par. Of course, I say that every Open.'