The fifth hole at Merion is a tough hole for several reasons. In the qualifying or from the Legend tees, you are generally left with a shot of 195 yards to a green that does not receive long irons shots well.
My success on this hole has been to play short and right allowing the ball to land in the fairway roll up on the green and break almost dead right to the hole. If I pull this off I am generally left with a 5 to 12 foot putts that I make about 1/3 of the time, the break is so severe and the fear of hitting it too hard that I'm not sure I will do any better.
If you fly it right at the hole, it will come up short or left virtually every time. If you are playing from other tees, you are often left with a much shorter shot that you can fire directly at the pin, however being off 2 yards short or left will put you back in the fringe.
In Open qualifying if I'm 4 under going into 5 I am going to play it conservative, worse case end up short with a fairly simple pitch shot, putt or flop from about 30 feet that is not very difficult to compete in 2, take my par and move on to #6, which also has some serious issues.