I know that people are jealous of how fun TBN is, but shielding and self-healing are very different mechanics. The first is proactive, the latter is reactive. It's like comparing Zarya and Roadhog.

What they should do is keep DRK thematically consistent around shields and punishing opponents for attacking them, right across to invulns. Give Living Dead to a tank that wants to be thematically self-healing focused.