Shannon Sharpe had a change of heart about Drew Brees -- now saying the QB deserves a 2nd chance ... just days after blasting the NFL star on national TV.

Remember, Sharpe called for Brees to retire and walk away from pro football forever on his FS1 show "Undisputed" after Drew condemned NFL kneelers during an interview with Yahoo Finance.

"It wasn't what he said," Sharpe said Thursday ... "it was how he said it. He was defiant. I will NEVER respect the man."