They were also pretty banged up in the secondary that day. Not sure it would have mattered in the end (it takes a lot of injuries to go from winning a game to losing by 30), but after Jackson the three highest snap count CBs were JJ Williams, Myles Bryant, and Justin Bethel. So it didn't matter if JC was taking out his man, there was always going to be an easy matchup for Allen to exploit. Dugger having a clubbed hand probably didn't help much either.
It remains to be seen how this secondary will shake out, but I think the hope is that even though they won't be as talented at CB1, all three of those other guys will be upgraded.
Outside1: Mills < Jackson
Outside2: Butler/Jack Jones/Mitchell > JJ Williams
Slot: Jon Jones > Bryant
Depth1: Butler/Jack Jones/Mitchell > Bethel/Ross/Bausby
A lot to sort out, but that's the hope.