The fact is that winning three games in a row is incredibly hard.
Let's imagine that they face two teams that they are totally superior to -- give them a win probability of 90%. And let's imagine that they face one that matches up to them pretty well but is still inferior - give them a win probability of 60%. In that case, the chance of the team winning all three games is still under 50%. As it would be if they faced three games that they had a 75% chance of winning individually (42% probability).
So, although we know that the team and the coaches will do everything they possibly can, and they are rightfully the number one seed, it's still a toss-up.