Shots fired from NFL legend Tim Brown -- who just blasted Floyd Mayweather as one of the most BORING fighters ever ... and said he refuses to pay to watch him fight Pacquiao!!!

Brown just appeared on "105.3 THE FAN Dallas/Ft. Worth" -- and sounded off on the head of The Money Team ... saying, "He's BORING man! He never gets hit. Knock somebody out, will ya?!"

The former wide receiver went on to explain that Floyd is more of a "piddy pat" fighter who never goes in for the kill -- "If I'm gonna pay for a boxing match, I wanna see blood."

Damn, Tim Brown.