A test:
1 German company and 2 Pionier platoons at near full strength (a couple of losses to make them fit into one hex) and A quality vs. a 50 men C quality Guards Rifle platoon.
Values:
121 - 31
Attack modifier 50
Defense modifier 0.
Defender disrupts and retreats: 27 out of 100 times.
Average German casualties: 6.14
Average Soviet casualties: 16.25
Average casualties for the first 50 and the second 50 turns (to split the results at 50 for the sake of the example) are similar, so the average casualties are fine and work within the system, it's the Disruption result that matters and that's giving very variable results.
The casualties include casualties from defensive fire when the defender was targeted for an assault, but don't include casualties from moving into the hex they're assaulting from.
As can be determined, the result Dog Soldier had is uncommon and on the "good to excellent" end of results. Yet, the forces are identical to a situation where he would have had a 5 - 8 result. The variability influencing Disrupting the defender with assaults (against bunkers) can feel like it influences the game too much for a die roll (the game shouldn't be decided by if you get Disruption rolls early against the bunkers you need to assault).