A half par hole is one that has a scoring average 1/2 a stroke above or below par. Large opportunity to gain on the field.
When we were doing the planning for PGA West, after Mr. Dye had described his ideal finish for me, I asked, are you looking for holes where you could have a two- or three-shot swing on the leaderboard in one hole? And he said, yes, that's exactly what I want. On half-par holes, ideally, you could make birdie (or eagle), and bogey (or double).
On the 13th at Memorial, nobody made two as far as I know, but there were also some big big numbers. I happened to catch Brooks Koepka there both days, and he played the hole perfectly. On Saturday, with the pin back right, he hit driver pin high and made sure to miss it right, and then hit the most beautiful little wedge shot high up the bank to two feet. On Sunday, with the pin down toward the front, after some hestiation he pulled 3-wood, hit it fifteen yards short of the green right in front, and two-putted from there.