Basically his fitness guy pagialiani saying roger is finally getting back to his level of fitness that was gone for most of 2013.
Also another another article I can't link yet cause its a subscription only site says the following about federer:
- feels super fresh and started training on the courts 10 days after world tour finals
- speed, explosiveness, hunger which they point out was gone for all of 2013 as federer was actually feeling burned out even in 2013 aussie open from his 2012 season has returned.
-new raquet is giving him 6-8 kph more on serve. Roger also says he feels his serve is better than it has been in some time and that will be a key for him.
-he's hitting his forehands with much more pace mostly due to the new raquet and better explosiveness after being unable to train with pagliani 100% which he did not do for almost all of 2013 aside from mostly some rehab which federer says really got him behind.