Why was Iron Tread considered bad in the first place?
I don't using both Tread & Tusk in OU because mainly i'm playing screen HO, but I have more problem facing Tread than Tusk.
Tusk can lose 1on1 vs Grimsnarl using spirit break with reflect is on, but Grimsnarl cannot defeat Tread because of its steel typing, not to mention Tread have better speed then Tusk that it can spin in front of base 100 speed mon
Iron Treads really just suffers from this problem called "being outclassed".
Like sure, it's a decent and functionally usable Pokemon that does what it does well, and it admittedly has a few advantages over its main competitor, Great Tusk, but 99% of the time your team is going to want to use Great Tusk (and now Landorus-T has joined as another competitor for an all-round universal bulky Ground-type). Great Tusk contributes more to a team under 99% of circumstances and is so exceptionally good at what it does that it's basically a universal glue as a Ground-type that contributes a variety of roles to a team, to a point where there's very rarely a reason
not to use it.
Iron Treads has a few advantages like its Steel-typing and Speed, but those are situational when Tusk is just a better fit on OU teams under almost every circumstance.
And as I said, Landorus-Therian is back as well who has historically before Great Tusk been OU's universal glue Ground-type, and despite losing a few things is now likely gonna share the role of universal bulky Ground glue and leaves even less room for Iron Treads in the tier.
So it's not really that it's an ineffective Pokemon, but in a case like this where you have a competitor who is
so good at what it does that it's almost always a must-have on a team (in this case, Great Tusk), you need an incentive to want to use Treads over Tusk and the incentive to use Treads is very little comparatively when you look at what Tusk can do and bring to a team.
Landorus-T and Great Tusk both being here and being as excellent at what they do and hence splashable means Treads, having as little to stand out from them as it does, generally has very little
incentive to actually be used on a team because very rarely is there a situation where you could use Treads and that teamslot isn't just better off being given to Tusk or Landorus-T.
In essence it's just outclassed. If it were to drop to UU it would fit in much better as it would have less competition and would be able to reign as a strong bulky Ground-type in there, boasting good firepower and bulk combined with a great Speed tier. Right now all they have are Hippowdon and Donphan and Donphan is...obviously inferior to Treads lol.