It's the luck of the draw. Had a guide friend who had a customer in AK that was from MN. His very FIRST king was an 89# hog. It's always first timers luck. Nope, can say I've never had anything that big on a fly rod. Have had a 60ish # king on though. Know how he fealt. Can only imagine what a bigger one would be like.
I have fished the lower Rogue where the fish was caught. My personal best their was a little under 30 pounds. (estimated - we C & R'd)
One of my buddies landed and released a (tape measure estimate) 52 lb king a few years ago. He released the fish right in front of a jet boat full of tourists - who proceeded to go nuts with indignation. It was worth a good laugh for us!
That hole is the perfect spot to land a big king on the fly. The water is slow & deep, only a very mild current. Notice that he had a relatively light rod. With a pram and the right technique, you can get right over the top of the fish and use your boat to tire the fish out.