I think the number for execution alone should be 100%. Your strategy can be flawless, but if you don't execute the shot what have you achieved? Sure, you can say, "At least I didn't make a mental mistake." But, the result is most probably a score higher than you wanted.
I think that to score how you want to score, your execution needs to be 100%. Poor startegy can certainly hurt you, but even if your strategy is flawed, if you hit the shot the way you want to, most probably your result will be a good one. You probably just hit the lower-percentage shot.
Phil at Winged Foot was poor execution. Sure, his choice to hit driver can and should be looked at with skepticism, but if Phil had executed the tee ball with his driver he would have been in the fairway, and most probably would have won. Same with Van de Velde. If he had made a better choice to lay up with his second he probably would have won, but if he had hit his second at the green he would have won, too.
I don't mean to say that you can't make a bad decision. To score well you have to make some smart decisions, but even more so you need to hit good shots.