A number of pieces of evidence currently point to the fact that Frost DKs might be emerging as a counter-meta spec. First, Frost DKs have been increasing in their overall representation over the past few months. At the end of January, their 2v2 leaderboard representation was roughly 1.2%, while at the end of February it had increased to 1.7%. In absolute terms, that's not huge, but in relative terms, it's an increase of almost 50%. In 3v3, Frost DK representation has gone from 2% to 2.7%. Of course, there are all sorts of reasons why the leaderboard composition might change, so let's move on to some more specific pieces of evidence for the emerging strength of Frost DKs.
One particularly noteworthy piece of evidence is that the growth in raw damage output has been significantly higher for Frost DKs as the season has progressed compared to other specs. This probably mostly reflects the increase in average ilvl. Below we're showing damage of a few key specs over the course of the season in 2v2.
It's evident from the plot that Frost DKs have a much steeper slope than other specs. On average, Frost DKs gained 34 DPS per week between week 1 and 9 of the Shadowlands expansion. Compare this to Windwalker Monks and Arms Warriors who each gained roughly 15-16 DPS per week, and Affliction Warlocks who gained 9 DPS per week. While in Week 1 of Season 1, Frost DKs and Windwalker Monks did the same amount of average DPS in 2v2, Frost DKs now do around 15% more.
A third piece of evidence that suggests Frost DKs might be a sleeper spec is how well they seem to play into the 2v2 meta. Looking at our 2v2 comps overview, we can see that the best matchups for Frost DK/Holy Paladin are some of the most common comps at high rating. The data for Frost DK/Discipline Priest looks broadly similar, but there's far less of it at this time.
While they suffer a significant disadvantage against some meta comps (Windwalker Monk/Discipline Priest and Retribution Paladin/Discipline Priest), they have a substantial rating advantage against comps such as Mage/Rogue, Arms/Healer, and Windwalker/Holy Paladin. On average, Frost DK/Holy Paladin has one of the highest average win rates when playing into meta comps ("Meta win rate" above).
So will Frost DKs emerge as a counter-meta spec in 9.0.5? In 2v2, Frost DKs struggle with the lack of a Mortal Strike effect, which negates a fair chunk of the extra damage they do. Nevertheless, their performance against meta comps is undeniable, and it seems plausible that they will emerge as a counter to the rule of Arms Warriors in 2v2.