Allen retracted his bishop to the d1 square. Carrion responded by also retracting one of his pieces which was his queen to the e8 square.
After deciding that his defenses were now solid, Allen attacked Carrion's pawn by moving his pawn to the c4 square. Of course, Carrion took the c4 pawn using his b5 pawn.
Allen wouldn't have pushed his pawn if he wouldn't get any trade for it. So, he took the pawn on a5 using his rook. Carrion didn't want to trade rooks so he moved his bishop to d7 to connect his rook with his other rook.
So even if Allen took his rook on the a8 square, Carrion could capture Allen's rook with his other rook so it would only result in an equal trade.
Allen also didn't want to trade rooks so he slid his a5 rook to the c5 square. Carrion decided to trade rooks with Allen as he attacked Allen's rook by sliding his d8 rook on the c8 square.
