Oy. Sastre beat Zubeldia in a GT practically every time when both of them finished. I think it's something like 11-2 in Sastre's favor by my quick (and sad) count.I think that even if Roglic's career ended now, he's ahead of Sastre. Sastre just didn't win much. He wasn't a one day racer, and I don't even think he won any one week races (happy to be advised otherwise though). He was sort of a little bit better than Zubeldia (and also admittedly far more attacking), and happened to win a Tour (the TOURRRR!).
But Roglic is a truly dominant rider of the peloton. There's all the one week stage races that he wins (plus the other ones that he almost does), plus he's won LBL, and Olympic TT gold, and 3 Vuelta's.
Sastre was on another tier in GT's compared to Mr 'Finished 4th in the Tour once'.