What sets good modern games apart from the crappy old ones is that theres less random chance calculation.
Things like the new Deflect mechanics is only adding more of random bullscheiBe.
If you want to rebalance the game so bad use other mechanics instead,
like attach penalties to nanos/perks, or
must be behind target
must be hehind target + in shadow to sneak
must be snared/rooted/not moving target, or
target must be passive
target must step on trap for snare.
Target hp below 10% for charm,
Blind reducing targets character view distance
Must not be in line of sight.
Check Melee skill vs enemy AR to block fast/medium attack
Check evades vs enemy AR to evade medium/heavy attack
Must be in 5meter range
Must (not) be in 5meter range