Odd, I don't see S9 in stock on Bitmain on a consistent all the time basis, which WOULD indicate overcapacity.
They're STILL selling out every one they can make.
The ONLY units they're not selling out on are those old "relabled S7" things that are UNPROFITABLE for most folks because of their low efficiency by current standards.
Dude, it used to be that it takes 3 months to receive an antminer S9.
Which STILL is not "overcapacity", it is "demand dropping to CLOSE to capacity".
NOT the same thing.
If current Bitcoin price trend continues, they MIGHT actually hit overcapacity in the next 2-3 months - but they're not there YET.
Also, you might want to pay attention to the fact that the length of time for them to sell a batch increased a LOT when they moved to the "require payment in BCH", even though Bitcoin price was still rising at the time and demand was still INCREASING.
Instead of "sold out in a few minutes with massive website clog delaying the sales" they went to "needed a few days, then needed weeks" to sell out a batch over the next 2-3 batches after that - DESPITE a still huge demand level.
They've also had more competition appear in that timeframe, AND new models from existing competition that were comparable on performance to the S9.
There are a LOT of factors behind why S9 pricing has dropped the last month and change.