i think the guy who played in the 2011 FO semis was capable of beating any version of Federer on clay.
His last best performance on grass was probably 2008 wimbledon.. I don't think the 2009 Wimbledon or 2012 Wimbledon Federer could've touched the 2006-2008 guy.
On hard courts it's the 2010 AO version. He was fantastic