only two things he's improved is getting free points off his serve ( he was slightly more clutch back then ) and tactics at times ( not always )
anyone who thinks he's improved his bag of "tricks" is sorely mistaken ...
for example, there is this wide misconception amongst many that he developed his dropshot in 2009
look @ the 2 drop shots vs safin in 2005 after 3:10 for example :
http://www.youtube.com/watch?v=GEeyM3KFovk
somewhere in the match , there's also a BH lob hit on the rise with the flick of the wrist ...
also these 2 drop shots ( one of them in an exo in 2007 )
Federer's virtuoso drop shots against Sampras and Agassi
all the shots were jaffas ...