The way Phil Mickelson putts at St. Andrews will be the pivotal factor in whether he wins or finishes in the top 10 at the Open Championship.
Phil's Achilles Heel at the US Open at Pebble Beach was without a doubt his inability to consistently make putts, especially those putts in the six to ten foot range (if you remember, he was reported as saying that he had putted "just awful").
One does not win a major championship, or any event for that matter, by putting well in one of the four rounds, and Phil understands that concept better than most on Tour.
The inherent unpredictability of Phil's game means there is no sense of assurance that he won't make the same mistakes he made at the US Open, let alone what happened last week at the Scottish Open.
Last Friday, in his second round at the Scottish Open, Phil was on the verge of making the cut, until he approached the 18th hole. Lefty hit three separate tee shots leading to a brutal quintuple-bogey 9 and ultimately a missed cut.
So much for momentum heading into the Open Championship.
Another issue for Phil will be accuracy, both off the tee (ranked No. 180 on Tour this season) and into greens (ranked No. 58 in GIR). On a course world renown for its excessively dry and windy conditions, Phil will need to introduce a level of control that is not an inherent aspect of his game if he truly hopes to contend for the win.
The only reason I imagine Phil can remain near the top of the leader board throughout the event is that he is one of the best, if not the greatest, recovery players of all time.
If you start to doubt him, just think back to the phenomenal shot he hit from behind the tree at Augusta National on the 13th hole of this years' Masters.