I was surprised, Atletico asked for that result effectively. Second half they dropped deeper, changed to a 4-5-1 and got under worse and worse pressure. As I said earlier, Villa was making runs and the wide players weren't playing the ball in. There were a good 8-10 chances to play Villa in that they didn't take, he may or may not have scored any of them, but it was important to make the defence worse, push them back a bit further, which pulls their midfield and attackers a bit further back.
They've been so good all year because while they've defended leads they haven't changed how they played that much, they've still attacked. The occasion got to either Simeone or the players, or both. Players have a tendency to keep dropping deeper in these situations but Atletico have been so good NOT doing that all year. The way they played the second half was asking to eventually concede and had Bale not been so **** up to his goal, they'd have won 3-1 at least in normal time.