Because I saw the same offense I've seen in every game this year. I didn't necessarily expect a complete overhaul of the entire offense for the playoffs, but with 4 weeks to prepare, you would think maybe they would throw a few wrinkles out there to keep Clemson honest on defense. Instead, it was a very vanilla, predictable offense for the entire game. Add in the fact that Book developed happy feet early and the defense still doesn't know how to properly defend the pass, and frankly the outcome that we got seems fairly predictable.
The question you should be asking is this: why is a fanbase that has seen its fair share of shitshows in the last 2 decades really so surprised about this outcome? This same fanbase was nearly unanimous in their score predictions that ND would win this game. What in ND's history over the last 25 years really suggested this fanbase should be that confident, excluding obvious fan bias?