There's a valid difference between good and not missing a shot
ever
and getting all crits on your melee
people that are really good rarely miss shots, and melee has notoriously high crit rates, it's entirely likely that all the melee hits
you saw were criticals and all the shots
you saw him make were headshot kills
almost every hack claim that has ever been made is wrong so there's really no reason to believe you if that's all you have
now when a heavy is making jerking movements while looking at the ground holding his minigun so that there is no bulletspread and every bullet goes in a straight line and hits the target,
that's hacking
Poll