Surprise resets people expectations. This surprise creates the
psychological momentum that increases people's expectations of our
continued success, but only for a limited time. When we have momentum,
others tend to support us more readily. We tend to act with more
confidence and persistence while our opponents tend to act with less
confidence and persistence. We must take advantage of this temporary
situation while it lasts.
In sports, if last year's champion wins this year against an ordinary
opponent, it doesn't create momentum. Similarly, Microsoft's mobile
environments created no momentum because they were simply more of the
same rather than something surprisingly new.