Simon got two wins over Fed being on peak of his play. Simulteneously Federe was maybe in his worst form ever after becoming top player since 2003 till then, his confidence was near zero after Wimbledon and he had big problems with back during WTF. Though AO-10 obviously showed that match-up issue is there too.
I guess first or all the main reason in no free point against frenchman. You can see plenty of 10-15 disappears from Federer during almost all his matches, but multiplying it by opponents mistakes it doesn`t cost him a lot. Unlike a lot Gilles on this stretch takes all that possible. Never missing a lot in their matches he became real wall giving Rogie a chance to beat himself.
Simon is great counter-puncher and he can easily use the speed bighitters give to ball. Problem for Fed - he must either decide points quick not giving to Simon finding his rhytm on baseline or he faces the situation where in neutral rallies he plays primarily from backhand wing shot after shot having no light variants to finish point in one shot.
Simon`s game makes pressure on Fed - he realises that he must take match away 100% himself, no gifts. It leads to more agressive play, logically - higher level of EUs ig Peakere isn`t on court only. I wouldn`t say that Simon`s return of serve frustrate Fed, this his weapon isn`t beaten, but Gilles reliability on baseline overall - is. Also I should add quality of frenchman`s passing shots - he is fifth-sixth best player in this department, IMO.
Smth like that.
Yes, but that doesn't explain why Simon should give Federer trouble when another 'grinder' - Ferrer - who also doesn't give away free points, also is rock solid from the baseline, and also feeds off pace is absolutely owned by Federer...?