Did you take a look at those graphs in the article I linked? There are only a few states where the OD rate has been declining, but it’s still an overall upward trend almost everywhere over the last five years.
Where is the phenomenon you describe actually taking place? I suppose California, Oregon and Washington have leveled off a bit, but then you’ve got places like Maine and Colorado marching upwards. There’s a lot of other factors in play here too.
I’m not saying legal weed is somehow detrimental, mind you. I agree that it should be a good pain relief alternative for a lot of people, and I personally know a couple of people who have gotten off prescription opiates and switched to weed. I’m just saying that legal weed is, at best, a garden hose trying to put out a forest fire.
The actual events in the real world don’t seem to care that your sources believe legalizing weed will lead to lower OD rates. We’ve got medical marijuana in 30 states now and the OD rates are climbing in nearly every one of them. And this increase in deaths is taking place in a country where more and more first responders are keeping naloxone on-hand, which is often the difference between an overdose and an overdose death.