I came across a rare YT video of one of Steve Ovett's late career races from 1988 :
https://www.youtube.com/watch?v=kxE8iXShv8o
The Cork City Sports 1988 Men's Mile which was won handily by Steve Scott with Ovett something like in 8th place. Both Scott and Ovett were around the same age, here around 32/33. Mo Farah is 33 and favourite to repeat his Olympic double this year. Seb Coe in 1989 at 33 ran low 1:43 for 800m (faster than Ovett ever ran) and almost only lost the World Cup final because Bile (the world champion) impeded him in the home straight. Coe also famously won the AAA 1500m and last showdown with Ovett despite almost tripping and losing 20 yards with Ovett well down the field.
So how did Ovett go from still being clearly world class (if past his prime) in 1986 to a hack in 1988? He was moving back down after only a couple of years experimenting with the 5000m. He was still the two mile world record holder from earlier in his career and as last as 86 still possessed his blazing speed as witnessed when he destroyed Jack Buckner in the Commonwealth games, with Buckner going on to win Gold at the European Championships only weeks later (with Ovett dropping out due to the heat)?
Did he suffer a serious injury or illness in 86, perhaps that the Euro performance was the first sign of?
Also, what about the idea that Steve Ovett's sharp decline from 86 onwards cost Seb Coe his chance of defending his Olympic title in 88? It must have played a part in the minds of the selectors seeing his chief rival, only a year older and clearly over the hill in 1988 (and even the younger Steve Cram evidently past his prime already) and with nothing much from Coe at that point since 86 to demonstrate he still had it.