[MzTT]

I may be missing the joke here but what more can Button do apart from win races?

This is exactly the problem here. Before rating Button accurately we must wait until other teams have caught up with Brawn, if they do it at all. At the moment it's difficult to rate, how well Button is driving, due to the car advantage. Hell, even Piquet or Nakajima would win in that car, if they kept it on the road.

Brawn's pace is underrated and it seems they haven't shown all of their cards yet - so catching them would prove to be difficult. Remember the beginning of the Malaysian GP. Button got stuck behind Alonso for a moment, while Rosberg and Trulli were pulling away. After Button passed Alonso (relatively easily considering clear car advantage and despite KERS disadvantage), he was immediately behind Trulli, despite having been behind by a few seconds. This moment proved to me clearly that BGP is untouchable. And from there on JB sat there patiently until pitstops.

About comparison with Barrichello. Based on the first two race weekends one should say that the Brazilian was clearly underperforming (and maybe one suggests he is past his prime), unless you believe Button is the greatest driver of all times, because his advantage over RB was bigger than Schumacher himself often had.

But all in all, it's not a knock on Button. He is doing, what he needs to be doing - winning races. Regardless of car advantage. Just that we can't really rate him yet.