To add on the discussion about VGC viability rankings:
-Doc's tour had teams built a week or 2 after the first batch of HAs (and Competitive/Neutralizing Gas) came out, so shiny toy syndrome was over represented.
-Doc's tour also had evasion clause and sleep clause, which affected usage of some Pokemon which saw significantly more usage in PCL than that (Amoonguss being a big one).
-Most of the players who played in Doc's tour don't even typically use Mienshao in regular doubles, so it's not surprising that it saw almost no usage in VGC, sash had very little to do with it.
-You mention Mienshao not really being good because of competing for sash, but sash isn't even a very contested item, even in the viability rankings list. If you look at the full list, 6-7 pokemon at most (potential 6th being Pelipper which isn't on the list even), most of them either have little synergy with Mienshao, aren't that great, or both.
1) Whimsicott - Can easily run a bulky set with a berry (Occa or Coba) to free the sash
2) Venusaur - if you're running Mienshao sun, you're probably running a team so offensive that you can be fine with LO or a gem on either of the 2. They definitely clash for the sash, but it wouldn't be enough to stop you from running both if you really wanted to.
3) Chandelure - Chandelure often runs other items (Gem, Life Orb) so it doesn't necessarily cause a clash here.
4) Mamoswine - That one is definitely bad enough that you probably run Hitmontop instead
5) Raichu - Was a result of new toy syndrome. Definitely overrated, probably doesn't even want sash in its optimal team.
6) Excadrill - Excadrill can easily run another item, but Mienshao also probably prefers another item because of sand being annoying.
Because the sample size is so small, there is a lot of bias towards some players's preferences, which doesn't reflect proper viability, especially when half of the data compiled, if not more, is based on a different ruleset than the one the viability rankings is based on.