Black discards piece after piece for positional advantage

Move 10: he could have taken the advanced bishop with a pawn and that rook would have still been up for grabs in step 11.

Move 11: again he could have taken the bishop, this time with his own bishop, instead he opts to move it out of the way. Why on earth?

Perhaps he was just baffled by his opponent's apparent total disregard for losing pieces?