I dunno Brent. Theres some other ways to look at it. For me the 22-23 season can be considered very much outlier. Its unlike any other season he's had. McD hadn't scored 50G once prior to that and hasn't since. His peak is 41 goals other than that, a full 24 goals off that one year mark. Also in 22-23 McD had an outlandish 71PP pts on an all legend PP that broke many records. That alone was never going to recur to the same level.
So if we level out or factor the 22-23 season being outlier how much drop off, really, has occurred? McD has ranged anywhere from 108pts up over last several full seasons. He's recently also had 120 and 130pt campaigns. He/s missed games due to suspension and injury this season, he's seeing a much less effective Oilers PP where he's getting appreciably less pts. His scoring is struggling all season (the biggest difference being right there)
In anycase this season, prorated is not appreciably different than his 17-18; 18-19;19-20 campaigns.
Another consideration is that this is the only post cup final season we've ever seen from McD. The only truest fatigue season. Where its normal for players to have dropoff just because of how many games played. Contrast the raw games he's had to play the last couple seasons with say the Covid seasons where McD actually got appreciable rest and much shorter playoffs.
McD in one of the covid seasons only played in 60 games regular season and playoffs combined. Last few seasons he played from 90 to over 100games. Quantum difference and last couple seasons he's played the most hockey he's ever had to play.
My take is we're seeing cumulative fatigue and maybe a hand or wrist injury. But of the type likely to be chronic for him from now on in a league that allows its star players to be hacked, chopped, abused etc. McD can't be compared to all previous NHL superstars. Many of those had constant protection from harm on the ice riding shotgun. McD has never had that and suffers all the abuse prior superstars didn't have to, to the same degree.