The fact is that some teams hardly take preseason matches seriously, so using preseason to fully determine the performances of a team, I don't think, is ideal. It’s very possible for some teams not to do well during preseason, but during the main season, they will perform so well, even more than people expect. In fact, not all key players play in preseason, and one thing to note is that some teams' preseason matches are often against smaller teams. But let's see how Bayer Leverkusen's season will look, even though I don’t think doing well in preseason fully determines their overall season performance.
This is very correct, some teams do not bother about preseason games enough to put in all their efforts, they even make sure not to use all of their mainstay players in most cases so they do not get them injured or expose them to certain health risk and suffer through out the season due to the players heslt conditions which was acquired from preseason game. Judging a teams strength from a preseason game may not be okay but you can get an insight as regards their readiness by their preseason performance, some teams can be very good during preseason and fumble when the main season starts.