He already tried at 100%. He failed to finish the job in the last TT, and fortunately it happened. Roglic is a disgrace for an offensive cycling that captivates more fans to this brilliant sport. It's would be so sad and boring to see a defensive rider like him, winning the tour. Fortunately pogacar won that Tour 2020, and we also have remco and vingegaard that are not afraid to attack from far.
Roglic wasn't at 100% in that Tour. He crashed hard during the Criterium du Dauphine before the Tour. So hard that he had to abandon before the last stage even though he was in leader's jersey. There were rumours a few days before the Tour, that he won't even start, because of the injuries he suffered during the crash.
If he doesn't crash in the Dauphine, he wins the 2020 Tour, I'm sure of that.