Disagree. It was almost the perfect header from that position (although back across the keeper would arguably have been better) -- hard, downwards and on target, and the ball had already made it most of the way through Alexander's legs before it came off his back foot and away. If Saunders did exactly the same another 10 times from that position I'd bet at least five of them would go in.
Murphy should certainly have done better, although as the replay shows he ended up having to dig it out from between his feet slightly -- came right at him rather than sitting up nicely in front of him.