Daniel Komen… had two great seasons and never heard of again.
Gabe Jennings… was unbeatable in the US in the mile in 2000 from Jan- June and his career never resurfaced after that after many attempts.
Alan Webb… hate to say it but at his peak that 3:46 was the beginning of the end of his career. And after that there were glimmers of hope here and there but mostly BAAAAAD performances.
Jordan Hasay
Lukas Verzbikas
Regina Jacobs
Ryan Halls last year was BAD as well but that dude milked every ounce of talent he had from 2007-2012 trials
Edward Cheserek. Went from NCAA King to ordinary pro. I’m not sure if he’d technically be considered a fall off a cliff or a failure to launch, but either way it’s weird that someone who was one of the greatest college runners ever has had such little success as a pro.
Ches was/is an interesting case. When you watch videos or hear about his training, it becomes painfully obvious that he routinely went way too hard and ran him cyclically into injuries. He also ran 3:49 for the mile indoors right before super-spikes started taking off, but unsurprisingly was hurt not long after.