The new kid on the block Nicola Rizzoli got dropped into the Champions League group stage after only one year's apprenticeship doing qualifiers and youth stuff. UEFA must have plans with this young man.
The old school of Italian refereeing: Rizzoli showed a card in the 2nd minute. A bad foul is a bad foul and none of this lets-see-what-kind-of-match-this-is-going-to-be. That was good. But then, he could (and perhaps should) have shown another card a minute later to Eric Addo, a player who had no reason for taking part in this match, who had no clue what to do, who could not keep up with his opponents. It seemed Rizzoli didn't want to show a second card that early because of the lets-see-what-kind-of-match-this-is-going-to-be rule.
For the Italian referee there were two matches: the first 20 minutes the field was very wet and slidings often turned into bad fouls, not always intentionally. However, after a while most of the field got better and then hardly a (bad) foul was committed.
Eric Addo, who did get booked in the second half, is symbolic for the whole team of PSV: what were they doing in the Champions League? This is where the big guys rule.