I think Lee Sedol won the game earlier by destroying AlphaGo's territory in the center. The commentator (Michael Redmond) was quite impressed with what he did there.

Those moves look like AlphaGo had calculated a loss way ahead of time.

Sometimes its just not possible to stop the snowball rolling down hill. You cant always turn a retreat into an advance or flanking move, sometimes the first step backwards just turns into a full on rout.

I got the impression (possibly incorrectly) that AlphaGo was trying to throw curve-balls and be 'unexpected' in a way that might have 'forced' a mistake it could exploit.

Errors when already lost don't mean much.

Given the genius of LSD, probably the latter.