He was only 21 In 1984, when he won Gold in an Olympic record after 3 fast races in 5 days, and then ran under 1:43 three times including a 1:41.77.
He didn't begin running until his mid-teens, and the suffered injuries and even bone spurs on his feet that had to be corrected by surgery in 1982. One of his legs was longer than the other and he had to wear special shoes.
He clearly peaked at 21 in 1984 which is unusual for an athlete, and progressing at the rate he was.
I read an article from the end of 84 that stated the intention of him and his coach was to develop into an 800/1500 runner. The famous Nice race between Cram and Aouita in 85 was billed at the time as an attempt by Cruz on Ovett's WR. He trailed in 7th. Earlier that season he had won the Prefontaine Classic in a pb of 3:35. He probably jogged a 3:35 before Brazier was even born.
He then got beat by Cram over 800m.
He got injured at the end of August in Koblenz while beating Coe in a 1:42. He had intended to have a crack at Coe's 1000m WR after that. But he never got back to even his 85 form after that, despite managing to win silver at Seoul.
Shame he never reached his likely potential. Perhaps the switch to a 1500 focus was a gamble that ruined him, in addition to the problems he developed as a teen (which he attributed to running in flimsy shoes in Brazil). At the end of 84 you would have expected him to go on to run under 1:41, and maybe have the WR today.