Do GT fans not watch classics? This was pretty straight forward: Roglic had the most to lose, he would always be the winner on that uphill sprint. Mas, Yates et al tried to get away, but couldn't. So when an outsider attacks, you look at Roglic to chase, the only pressure you can add onto Roglic to possibly weaken him would be to make him chase. But he didn't. Same thing happens all over in the spring.
Anyone saying Mas, Yates, Haig threw away a chance today are not being realistic. They were not going to beat Roglic in the uphill sprint. They did in fact try to get away before.