Los Blancos have opened their LaLiga campaign with three successive wins, scoring 10 goals in the process.
Karim Benzema and Gareth Bale have combined for seven of those goals so far, and Isco says Ronaldo's absence is not being felt.
"Cris is an extraordinary player," Isco told a news conference, according to FourFourTwo.
"He guaranteed you 40 to 50 goals. But if we win, they'll say we don't miss him and if we don't win, they'll say we do.
"We're playing very well now; players who didn't score as many goals last year are now filling their boots. We don't miss him at the moment. I wish him all the best at Juve."