Murray attacks a bit and it works. Why he doesn't play like that for longer periods baffles me.
Because it's not easy at all to do, especially for a player with a defensive mindset like Murray? He can hit a big flat forehand winner fine, he can hit two in a row at times but he can't play like that over a long period of time. His consistency isn't high enough when he goes for his shots.
As soon as he missed one like he did there at 0-30 on Ferrer's serve (big flat forehand in the bottom of the net), it kills him because he can't stand losing a point in such a "stupid" way. And thus he reverted to being passive and lost that game.
It requires a lot of of commitment/belief/practice to go for it in every single point like Delpo, Berdych or Tsonga do. It's complete different mindset. Murray won't do that unless he's in a losing position/bad spot.
There again at 4-3 in the tie break, Murray hit his forehand with more pace 5 times but he couldn't hit the 6th one well enough.