If you're a super-skilled player and manage to defeat incredibly strong enemy heroes with minimal troops, but you still send just one hero forward while your opponent is slightly weaker tactically but manages to create amazing chains of actions, then with a more or less equal setup, I'd say there's a 99% chance you'll lose badly :p. But if he's clearly weak tactically, his chains of actions will quickly lead to his defeat :D. So, strategy and tactics in Heroes are inseparable.