2014 Carlesen Georgiev: missed opportunity?

Was working through a Carlsen game from 2014 (TCh-NOR Kvalifisering Eliteser (2014)  ·  Spanish Game: Morphy Defense. Archangelsk Variation (C78)  ·  1-0 ) and think I see a big blunder by Georgiev near the end - and that a different move might have saved him. The site I was looking at offers no analysis so I thought I'd ask here:

http://www.chessgames.com/perl/chessgame?gid=1753853

after carlsen plays b5 Georgiev makes a bad move with his rook - but if he had played Bf7 I think it defuses the attack and the game turns a bit, no?

If so, surprising that such a high level player would make such a mistake

you'll see if you click on the link!

thanks - i didn't understand what Ra8 was trying to do, it seemed bery passive like he was late for a plane or something