You need to grab the purple EPIC "In the Zone" and EPIC "Let it Rip" Strategy cards.
The "In the Zone" card gives your CBs and FSs +3 ZCV, +3 PRC, and +1 PRS... and the "Let it Rip" card gives your QB and full OL +2 THP, +3 IBL, and +2 DAC. But the kicker is that by having them both equipped you also activate another 2/2 tier which gives an additional +1 ZCV to your CBs and FSs. All my guys are at at least 90 ZCV now.
You can't search the auction house for Epic tier strategy cards now... so just search the name field for "Rip" and "Zone" and you'll be able to see the purple cards. A but expensive but they quicksell for 55k each so not too bad. I paid about 180k each for mine. You have to decide if that's worth it to you... but it was for me.
EDIT: You have to make sure both purple strat cards have the "ITZ" and "Zone" icons on them. Avoid the "Strong Arm" icon. When I made my original post the different types were not on the AH.