Tom Doak-
My index is 16.5, and I have played both Oakmont and Bethpage Black. At least for me, Bethpage played much harder. The difficulty I incurred at Bethpage was primarily a function of two things:
1. Forced Carries from the Tee - I'm thinking specifically of the 5th, where I stood on the tee and literally did not know where to hit my drive (I couldn't carry the bunker from the tee, and there was no layup area short or left of the bunker) and the 10th, where I couldn't reach the fairway from the tee.
2. Requirement to Hit Long, High Shots into the Greens - By my count, there are at least 15 holes that require you to fly the ball onto the green and give you no option to run the ball onto the green. There are also several holes where you're hitting to an uphill green and must fly the ball all the way to the green - the 2nd, 4th, 5th, 17th and 18th all come to mind.
The reason that I found Oakmont easier than Bethpage Black (although certainly not easy in it's own right - in fact, it's a beast also. I'm just talking in relative terms) is two fold - the ability to run the ball onto many greens and the presence of a few shorter holes that offer a sense of having a reasonable chance to make par.
1. Ability to Run the Ball onto the Greens - At Oakmont, by my count, there are at least 10 holes that allow you to run the ball onto the green (the following holes come to mind - 1st, 3rd, 4th, 7th, 8th, 9th, 10th, 12th, 15th, and 16th).
2. A sprinkling of relatively shorter holes that give you some respite from the brutish length of the remainder of the course. I'm thinking of the 2nd, 5th, 6th, 13th, 14th, and 17th, all of which present a reasonably good par opportunity, even for a higher handicap player.
I concede your point regarding the difficulty of the greens at Oakmont vs. Bethpage Black - no comparison there whatsoever. Oakmont's greens are far more treacherous and bring the possibility of 3 or more putts into the equation on every green. With that said, however, I still stand by my assertion that on balance Bethpage Black is tougher than Oakmont.
Jim