Counting this latest reincarnation, we've been treated to at least a handful of different ones: Aggressive Phil, Conservative Phil, Fit Phil, Fat Phil, Family Phil.
The only one we haven't seen is Finally Phil, the one who wins a major. And the wait for him could be over in a matter of hours.
'I think that heading into the final round, I'm much more at ease than I have been in the past,' Mickelson said late Saturday.
'I don't feel that anxiety. I haven't felt it all year. I feel very confident that I'm able to drive the ball in play, that I'm able to hit my irons the proper distance. I feel very confident in my putting and have all year. So,' he added, 'it's been a nice change.'
Mickelson has more of just about everything than when he left Arizona State a dozen years ago with a psychology degree - family, money, fame and game - except major championships. One other thing he never had was the lead, or even a share of it, heading into the final round of a major.
That changed Saturday, and the reasons why could lead to the defining change in his career.
It was never hard to figure out why the galleries love Mickelson so. He rarely took the easy route to the flag when something tougher was available. He made spectacular birdies and sometimes, even more spectacular bogeys, and every round was an adventure.
But when Mickelson hit town at the start of this week, he said he'd had enough. Flying a plane or laying down a big bet against long odds - those things still didn't scare him. What did haunt him, though, was the thought of coming back here after his competitive days were past and knowing he hadn't won it.
And so, besides the usual preparations, Mickelson said he had steeled himself by doing some math.
'What I found the last three years,' he said, talking about three straight third-place finishes, 'is that if I could have saved a shot a round, I would have had two wins and a tie.'
Mickelson IS different, but the crowds at Augusta National have yet to notice. They still try to carry him along, hardly recognizing he needs less help. All those promises to play the smart shot at the right time are finally being fulfilled.
Mickelson hasn't made a bogey in his last 32 holes. He's done that by making par-saving putts, both short and long. On Saturday, he made five ranging from 6 feet to 25 feet. Mostly, though, he spared himself a lot of heartache by staying out of trouble in the first place.
At the par-5 13th, Mickelson was just behind the green in two shots, facing a short chip to a flag on a putting surface that sloped severely downhill. To make birdie, he needed to get his third shot close. But rather than risk leaving the ball short, and facing an even riskier downhill putt on his next shot, Mickelson chose safe over sorry. The result was a chip shot that ran 40-feet past the hole, followed by a two-putt par.
Two holes later, the choice was even more stark. Leaving a birdie on the table at 13 made a birdie at the par-5 15th seem even more important. But an errant drive there left Mickelson in the left rough, in both a figurative and literal jail. A stand of pine trees stood between him and the green like iron bars.
Even with all that, Aggressive Phil would have favored the circus shot and fired at the pin. Instead, Mickelson punched out with a wedge on his second shot, wound up making par and moved on.
'I've always been trying to hit the ball hard and make as many birdies as possible. It's a much easier game just keeping it in play. I wish somebody would have told me this earlier,' he said, waiting for the laughter in the interview room to die down. 'It's just so much easier.'
Sometimes, there's no other way to learn things but the hard way. Mickelson was blessed with so much talent, the temptation was always there to use every drop of it. What Finally Phil may have figured out is that sometimes less can be more.
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