Peyton Manning looked absolutely nothing like one of the greatest athletes ever on Tuesday ... botching the ceremonial first pitch at the MLB All-Star Game -- and it was pretty terrible.
The former Broncos QB was tapped by baseball officials to kick off the big night at Coors Field in Denver ... and, boy, did he disappoint in the role.
Check out the clip ... Manning took the bump, reared back with an ugly wind-up, and then fired a fastball that didn't even reach home plate.