I assume you mean the general, not the admiral.
Admiral:
Global effect: +50% speed to subs not carrying a specialist
Local effect: 200% speed
Promoted from: Navigator
General
Global effect: -10 enemy drillers when one or more specialists are in combat
Local effect: 150% speed
Promoted from: Lieutenant
If in fact you do mean the general, the most likely answer is that the player attacking did not have JUST ONE general, but instead had THREE. The global effect of the general stacks, so for every general that player controls, a specialist will kill 10 drillers.
1 - 10
2 - 20
3 - 30
etc.
Hope this helps.
"No man chooses evil because it is evil; he only mistakes it for happiness, the good he seeks."
-- Mary Wollstonecraft