Yeah, that's part of the problem. Stamkos isn't a set up guy, but he's trying to be since he knows he can't pot 60 in a season.
All those assists last year probably fed into the erroneous idea that he had playmaking hands, when really it was just Kucherov playing out of his mind + some puck luck. That's not to say Stamkos didn't play well. He's just not a legit 60 assist, or even a 50 assist guy. If Stamkos is playing his A-game, most of his assists are coming as a result of rebounds, because goalies can't handle his shot even when they're stopping it. We're not seeing that as much lately, which might be because the one-timer is a lot more telegraphed these days (but also might be because it's not quite what it used to be). Goalies are getting into position and smothering the rebound on him more now, and covering for faceoffs.
Using the Ovy comparison again: Ovy's shot creates chaos most times he gets it on goal, because goalies are just throwing limbs in front of it, rather than containing it. It used to be like that with Stamkos too, whereas now they have that extra fraction of a second to properly set up for it. So now his PP goals are often coming when he just legit beats the goalie square rather than getting the shot off before they can set up.