Setting aside the thunderhead mini-boss, you really shouldn’t be struggling with 10s in a premade. 15s are skill-testing in current gear on the beta especially if your comp runs melee but you shouldn’t struggle that hard in a 10. I would guess you aren’t properly rotating kicks and stuns since avoidable damage does giga-damage.
10s definitely seem very hard for the weekly15noleavers players though. DF S1 is going to mop the floor with Andys, both welfare players and raiders who don’t take M+ seriously.