I finally got it. Federer is behind the blue clay
He needs clay titles for his resume and the only way he can get them nowdays is to install this slippery blue staff
Tiriac is in Federer's pocket!
Seriously, again, it was Federer who always used the "unsafe change of surface" card when DC was concerned. Funny how in his memory he sees himself adopting to a different surface every week
Even juniors don't do that! Once you go out on the clay, you simply don't play hard tournaments.