The more a player is on the ice, the more they should score. A player who plays 20 mins and scores the same as a player who plays 15 mins should be questioned. Coaching decisions for deployment are often imperfect and its a great way to identify players not getting they should be getting or players getting to many minutes
The ability to maintain Pts/60 in additional minutes has actually shown to be repeatable. People often say "Player X has high pts/60 in bottom 6 duties because he plays easier comp and if he gets more minutes hell face tougher comp so itll go down". Yet fail to realize, if that player goes into top 6, theyll also get better quality linemates. And QoT and QoC can often wash out