you could flip that question around ad say, how many not good holes is there at Merion
i will start this by saying i think there are many good holes at merion, a few world class holes, and several not so good.
i personally (in my opinion) think #3, #4, and #11 are not so good. #4 and #11 require you to hit a 200+ yard blind shot to a sliver of fairway. i just don't think that is a good design tactic. i don't mind blind shots, i just don't like them to such narrow landing areas bordered by penal rough. many of the blind shots i have played in the UK have landing areas that are blind but only have one or two small pot bunkers to navigate or are much wider landing areas. and for the record i missed both #4 and #11 fairways and did make par. so its not sour grapes.
i personally (in my opinion) think #6, #10, #14, #15, and #18 are world class holes. #10 gives you so many ways to play it with risk and reward. #14 has the best green on the course (in my opinion) and #15 just fits the land and my eye really well. i am sure #18 from the US Open tee is one of the best anywhere in the world.
we played the next to the back tees and i hit some version of a wedge in on #1, #2, #4, #7, #8, #10, #12, and #13. that is a lot of short irons for a top 15 golf course.
#12 green will have to be flatten if they are going to have the greens roll at US Open speeds.
all in all, i just believe (in my opinion) a top 15 golf course needs to have more world class holes. royal county down (all), pine valley (all), national golf links (minus one hole), portrush (minus two holes), augusta (minus one hole), etc
AGAIN, this is just my opinion and i am not trying to say merion is a bad track,
remeber not everyone thinks French Laundry is as good of a dinning experience as the reviews, nor does everyone think 67’ Chateau Lafite Rothschild is the best wine they have ever had. none of this is fact, only opinion.