Peter,
I was out yesterday also. My second visit. I'm not sure the best pros would have been more than one or two under, with those conditions. First, with only two par fives, that takes a couple possible birdies out of the mix. Also, it seems to me that in order to score really well at Crystal Downs, one needs to possess an awful lot of local knowledge. There are just too many crazy rub of the green bounces and rollouts, and the greens are pretty complex. The penalty for very small mistakes can be extreme.
One of the Gentlemen I played with has been a Member for 11 years. On #1 he chipped up 3 feet past the pin on his third. Tapped his putt, the ball nearly stopped two inches from the cup, but low, and then kept rolling to the front edge of the green 35 feet away. Small mistake, big cost, he made 6. And he was a good player, shot 76, played the course hundreds of times, knew what would happen, and he still got screwed.
The modern PGA pro is more likely to score low by hiting everything to 10-15 feet and making half the putts. No way anyone is getting 10-15 feet away on every Crystal Downs green, and for sure they are not making half the 15 footers. Too much speed on too much slope.
Another of the Gentlemen I played with shot one over his age, 80, he played the forward tees, but had a blast. Made tons of great putts, and was amazingly liberal with his off the green approaches with the putter, from 30-40 yards in front of the green. Pretty cool to watch. Seems to be one of the shots one needs in order to score well.