"Football is never totally rational," said the UEFA president, rejecting the idea that there were 'big' teams and 'small' teams.
"Trying to give a rational explanation for results is never easy.
"We have to respect what happens on the pitch. There are always people who are happy and people who are unhappy.
"We talk about the small teams, but I don't think there are big teams and small teams in the Champions League, I don't like the term small teams."
Spain's Villarreal and Romanian champions Otelul Galati were also out of their depth, losing all their games.
"There are games where the goalkeeper has a bad day, where the defence has been reshuffled, or perhaps a team has already been eliminated by the last match and are totally unmotivated," said Platini.
"You can see it in a positive way or a negative way."
"You don't win a match in the Champions League because you are a big name. Nobody is entitled to win all the time, I always respect the clubs from Cyprus and Switzerland," said Platini.
"There are always newcomers and I'm not saying its a bad thing, nor a good thing."
