Doing research will help you analyze historical data reveals pattern that can guide your predictions, there are history that will help you make good prediction, Research helps you rely on facts rather than emotions.
There's no such thing as pattern. Upset always happened even between a deadly Favorites and weakling Underdogs.
Though good point on mentioning game history and past performance. It's one of the good recipe in making predictions.
But you know what's most important?
Stick betting only with sports league that you have "KNOWLEDGE" with.