Allowing Counterplay

I have always known one of my bigger weaknesses was allowing my opponents too much counterplay.  While playing a blitz game (5|0) this morning, and getting an analysys of the position from the cloud in Chessbase 13, I realized the "strong" move I thought I had played, which won the game, was indeed not as strong as it looks.  First the position that led up to the winning idea, then a challenge, then we will look at the rest of the game.

Looking at this position, it seems as if Black is going to win an easy pawn, or prevent white from organizing his pieces by castling, or creating an attack.  Now, how to win it? White has one defender now, can black increase the pressure and win the pawn?

The natural looking Bf4 loses some ground.  Why is Nd7 required? It turns out that White can get some counterplay, close the file, and win the material back, with advantage after  Bf4 with  Qf5 and Ne5.  Nd7 is required to prevent the loss of material by playing Nf6 at the correct moment.  After Nd7, the pawn will fall. 

Interestingly enough, 13...Bf4 was not even a candidate move in a deep positional analysys of the game. 

Here is the full analysys: