Par on an individual hole level is irrelevant, all you need to know is the overall winning score: Rory won with 276 total strokes.
If you alternated 3 and 4 putts, you’d score a 252. (3.5 putts per hole x 72 holes) giving you an additional 24 strokes for some 5 & 6 putt holes.
This could be ignorant but I think any half decent golfer would win by a lot …
3 putt every par 5 and you make an eagle
4 putt every one and you make birdie
I think it’s conceivable to go -6 a day on par 5’s alone without much sweat and possibly better