In one of the Day TV videos (5:40-6:00 minutes) Day (what is actually his name?) says something like this:
Wall-in is almost always a vulnearability as much as asset. In the early game wall-in off prevents rushes, but in later stages of the game it is just a ... free depo there?
Could you clarify what he said (I couldn't here the end of phrase well)?
And why it is vulnerability?