Re: What is stopping Berdych from becoming a Top 4?
First 2 sets in Australia vs Nadal showed that he can keep up with Nadal playing near his best (lets be honest, that was by far Nadal's best match in absolute ages). But he just isn't consistent enough and yes, the slow courts have been unfair on him.
Either way he's had a good start to the year and if he continues like this then maybe it will happen. I mean it's all starting to fall into place, 2010 was a year of great results, 2011 of consistency, so now it's a matter of just putting it together, also helps that in the head he's a lot better mentally now too. Serve has improved a lot too, finished the last 2 years in the top 5 of 1st service points won, only other player that achieved that too is Federer. Is also currently number 1 in first service points won for this year.
As for the top 4 stopping him, I don't think so. As much as I like Murray I think Berdych at his best is better.