Not so sure about that. Not sure what superstars you are thinking about. I think more often than not, O numbers drop due to normal aging process, change in overall league scoring, etc.
Come on, if you play forward, you can either play safe, not go for 40-60 pucks, be in front of your check always, or you can take more chances. In the former case, your +/- will be better, but your offense will suffer. In the latter case, your scoring will be higher, but your +/- will suffer even more. The reason that risky defensive play hurts the +/- more than helps it, is that only in a small minority of scoring chances the puck actually goes in. So if you screw up defensively by cherry picking or trying for a low percentage interception, you may get a scoring chance say 10% of the time, and you will score on 5% of those, your scoring goes up 0.5%. But 90% of the time your screw up results in a scoring chance against, and if the opposition scores on 5% of them, your +/- goes down by 4.5%. That is not intended as a mathematical proof but rather as an illustration of my point.
Having said that, OV's play on that goal was revolting. I hate playing pick-up hockey because a lot of people play like that.