This move loses a piece to Qa4 check. Any block other than Knight-c6 (or moving the King) drops the bishop. If Knight-c6, Queen takes c6 check. If queen d7, Queen takes, and white is up a knight. If bishop-d7, Queen-b7, and white escapes.
---Homa
edit : resteemed, but with only 220+ followers.
Ah, good eye! I can't believe I missed that. Yes, your move is much better! I was thinking c7-c5 afterward but you are correct that would be much too late for our poor bishop.
Actually white escapes with a draw in this line, but I doubt white wants that at this point.
---Homa