The times SKT was giving ground to SSG were smart to not force fights. The best they could do then was stall put and clear minion waves.
Force a fight and lose a carry, you can't clear minions and turret falls. Force a fight and lose a tank, SSG can dive you under tower to clean out your carries.
The real problems were awful plays by Bang at neutral pits in games 2 and 3. He went full Bronze and got caught repeatedly in bad spots as well as poor use of his kit, and with no backline SKT was forced to retreat.