Watching all these previous super bowl wins on NFLN along with all the America's Game series and just from what I know there is ZERO doubt in my mind that the all time best defense, PERIOD, BAR NONE, was the Steel Curtain of the 70's. Just seeing the way these guys played with a mean, nasty, Im going to kick your ass because you're in my way, kind of attitude is something no defense has been able to duplicate to date. There was no frills, no tricks, just flat out tough, kick ass, you're going down and nobody is going to intimidate us defense that virtually nobody could match up with. We proved it with 4 Championships !
The only team to win 4 SB's in 6 years if my memory serves me correct. Whether you refer to Holmes, Greenwood, Mean Joe and Mad Dog as the Steel Curtain, or whether you think more like Mike Wagner who feels the entire defense was the Steel Curtain, it makes no difference because if these guys played today they would kill everyone.