MonsterEnvy
Legend
Rogues have never had any issues keeping up damage wise in my experience. Particularly if they have strong magic items as well.
If your SS / GWM chars outdpr the rogue then your mobs AC is to bad !
SS / GWM is still requiring to hit. Lets asume a mid Level Party with maxed attack stats so gives you +5 and +3 from the prof.
So that is +8 and lets say another +2.5 from bless.
That means +10 to +11 for them to hit in a normal combat Scenario. with GWM / SS this turns into +5 to +6 (due to the -5)
If they still hit reliantly with their Cookie cutter Modus on then your mobs seem to have AC of Maximum 15 if at all or your Players use fudged dice.
Make a test in your next game session before pulling up any obscure houserules for sneak attack:
use some e.g. hobgoblins clad in plate and shield, they do not even have to have that many hitpoints, but let them have AC 20 and lets see how your SS / GWM fare against these. Of yourse take an adequate number and spread them out so your AE Party members cannot trivialise the Encounter easily. Put in reenforcements if the fight goes to smooth due to lucky dice.
Try this and give us Feedback please.
my players were hitting AC 18-21 with disadvantage at level 5