In software, mis-managed expectation can be as damning as it is in sports and politics.
For example, coming into a political debate, each side tries to portray the other as vastly superior, in every way. If you can get the expectation low enough for your guy, he or she might "win" just by showing up.
In sport, where the outcome is measured more definitely, in points on a scoreboard, you manage expectation to play with the mind of your opponent. An over-confident adversary might relax, and create openings. The Knicks almost lost to the Celtics that way.
In software, I've seen it happen over and over. I've never had to deal with too-high expectations, but my competitors have. The first time I encountered it, with competition from a much-bigger Lotus Development, I was scared. But when we survived the competition without a scratch, I learned that just because everyone thinks you're going to lose, don't necessarily make it so.
I wasn't happy to see the expectations so high for the vaporware product Diaspora. The kids behind it were too young and inexperienced to know how much work there is in creating a finished usable product. Academia, which generally doesn't have much respect for commercial development, doesn't help. The result was awful.
Coach Bill Walsh of the 49ers had this down. Before a big game he'd always pump up the skill and courage of his opponent. Why not? Maybe they'll get over-confident. Either way, if he wins, he just vanquished a superior adversary. And if they lost, he gets to shrug it off with an I-told-you-so.
In sport, politics or software, no one cares how great you think you are. What matters is what happens on the playing field. Did you win or lose? And did you do it with grace?