Apparently TO because Michael Irvin was able to co-exist with his coaches/teammates.
TO is far from "the worst of today's professional athlete's" though. Has he ever been arrested? Has he gotten drunk and killed somebody with his car? Has he fired his gun outside a club? Has he raped, or even just sexually harrassed someone? (Hell, even Peyton dropped his pants in front of a female reporter.)
TOs "me me me me me" act gets annoying but doesn't really harm any innocents. His teams are dumb enough to sign him, and the only reason we ever hear about him is because ESPN and NBC (damn you Olympics) started the trend of sportscasters being more interested in drawing in casual viewers than giving sports fans what they actually want. He isn't on CNN being questioned about his legal problems.
Michael Irvin, on the other hand, knows all about legal problems.