Knowing the capabilities of the team/player that you'll be going to support always gives you decent idea if what might be the possible edge either they are the heavy favorite or they are the underdog.
Of course, but there are also people who deliberately choose team that are not favorites and are weaker for larger odd number but they manage to win the bet, whether this is kind of luck or match result that has been arranged from the start, but what is clear is that many incidents like this have occurred in recent times.
I have experienced many defeats with several favorite team and that is what has become belief for me to be more careful with betting choices, no matter how good someone makes predictions and analysis, there must also be chance of failure.