Sounds right... you ran into someone smart enough to slot one mono armour... there by making your build pointless.
5k unbuffed tranny isn't that great... against anyone running any armor.
People talk about neut armor and that works as a good general.
However if you know the only person really bothering you is only using torps... Monos still do more resist. If he was really worried about you and slotted 3 monos you would never ever kill him with an all torp build.
Even with out... Brace for impact will make your torps pointless while its up...
He may have also been running aux to damp... I run aux to damp on all my fed escorts and frankly no torp only bop is going to kill one unless they suprise me and are wise enough to not attack while my damp is up. If they are harrasing me with torps all the time like most torp b'rels do... I am just going to roll my hazards / aux to damp / omega - delta / and hazards... meaning my kinetic reisst is never going to be under 50... and if they where well put together I would swap out a console for an extra mono unit.