This is for all GCA'ers and not just Ron Whitten.
I have never understood what "tricky" means in reference to a golf hole. For those who know it, are the 1st and 11th greens at NGLA "tricky"? These are the two examples I can think of that some might agree upon. Perhaps the left green on #8 at Pine Valley also qualifies - I don't know.
As for Merion's short holes, I have never found anything "tricky" about any of them. In fact, under normal, non-U.S. Open conditions, they don't require any more precision off the tee or into the green than the longest, hardest par 4's (4 1/2's?).
Hit it in the best spot in the fairway in order to leave the best angle for the approach and hit that approach the right distance. Miss the green and you've got a difficult chip, pitch, bunker shot, etc. All 14 holes that aren't par 3's fit that description - where is the "tricky"?
Also, there is nothing really different about the greens on the short par 4's or #13 that make them more difficult or, somehow, "tricky". In fact #'s 7,8,10 and 11 are, arguably, the least difficult greens to putt on the entire course. Further, #'s 7 and 10 are two of the largest greens out there. Where is the "tricky"?