would you agree with the statement that

[brocktonblockbust]

Boxing started its sharp decline after Mike Tyson left the sport?

no I would not agree. I think boxing started declining about 1990 after Douglas beat him. You had a good young Lewis and Holyfield there, and a few exciting fights with Bowe, T Morrison and Razor Ruddock but the 90s then only had 3 or 4 exciting heavies, while the 70s had a dozen, 80s had Holmes, M Spinks, Cooney, Tyson, Qawi, Foreman 2, Mike Weaver, Witherspoon, etc

I say after Douglas beat Tyson it (heavyweight US boxing that is) went south.