In an empirical study (I don´t have stats about it), national teams lose against club teams. Club teams have enthusiasm, motivation and busine$$ to defend; National/professional teams don´t have. You can see motivation in national teams when they defend their countries, for example: African teams, Asian teams, Central American teams. They present spectacular games today, like Brazil presented in his 50s, 60s, and 70s.
Brazil and Germany would lose all games against Liverpool, Chelsea, Man U or Barcelona, today.