I'm not sure how to verify your comment since 538 was cut by ABC a month or 2 ago. But Nate Silver's pollster rating methodology is pretty much the same as 538's was during his tenure there and can be found here: https://www.natesilver.net/p/pollster-ratings-silver-bulleti...

It actually explicitly looks for statistical evidence of "herding" (e.g. not publishing poll results that might go against the grain) and penalized those pollsters.

In both rating systems, polls that had a long history of going against the grain and being correct, like Ann Seltzer's Iowa poll, were weight very heavily. Seltzer went heavily against the grain 3 elections in a row and was almost completely correct the first 2 times. This year she was off by a massive margin (ultimately costing her her career). Polls that go heavily against the grain but DON'T have a polling history simply aren't weighted heavily in general.