You are correct in many cases. Stuff happens, physical errors are made, strike outs happen, other teams will get breaks, perform well, etc.
If a player gives 100% all the time, keeps his head in the game each and every opportunity, then whatever happens, happens. I’ve been a Cubs fan for 50 years. I’ve seen some horrendous teams.
However, this season was particularly disappointing because the Cubs had far too many instances in which they lacked focus, did not understand the game situation, lacked fortitude, crumbled under pressure, (I’m including Maddon, too), and in turn played below expectations of what should have been a very good season.