For starters - it's Shanahan that deserves credit for the 28-3 lead...right? Did he not call all the plays that gave Atlanta the huge...err YUGE lead? Yes. So how can you blame him when Atlanta can't score in the second half?
Here's something my dad (who's also my football coach) has always said, "Players play, Coaches coach and Refs ref."
Did the Falcons players execute in the second half? No. Some plays but not enough to score. That's a failure by Atlanta's offense and a credit to New England's defense. It wasn't just play calling. Everybody says why didn't they hand the ball of three times in a row on their final drive? Well guess what? The Falcons very well could have handed off three times in a row on their final drive in the fourth quarter and... fumbled! Or got stopped for losses, or penalties. Possible.
The Falcon's offense is stacked with playmakers and that's why Shanahan wasn't afraid to throw.
At halftime my dad said something very interesting. This game is looking like a heavyweight championship fight where one guys comes out swinging just giving it everything he's got and I think the Falcons came out strong like that but will whither down the stretch like a fighter that runs out of gas. That seems about right. Down the stretch Atlanta gassed and New England took over the game.
You could sense the New England comeback even when they were down 28-12, then the fourth quarter came around and Tom Brady and the Patriots did their thing while Atlanta sat there and watched.
Everyone wants a reason after a loss, I just don't think you can pin that one solely on the shoulders or play calling of Kyle Shanahan.