Performance is the most preferable category of analysis, focusing on a few main questions:

• How often is this deck appearing in tournaments?

• when this deck does appear, where does it place?

Whilst the second question is the most important in terms of raw power, just consistent appearance is an important metagame factor. 

Michael Sanctify Control is one example of a deck with strong performance, which has contributed to it's strong metagame positions. Michael has consistently appeared in recent tournaments, and whenever it does it's a deck that frequently turns those appearances into top 8 placements, with notable top 4 appearances as well.

Whilst Michael has yet to move further than top 4 in a post GCD tournament, it has consistently been well within reach of those top spots, and players should be prepared to face against it both during the main stage of the tournament, and in the top 8.

Whilst consistent performance is the most ideal metric of success, there are a selection of decks in the meta which don't have a huge number of trophies to their names, but are still incredibly powerful decks.

This analysis plays off of two factors, non-tournament matches, as well as theory building, and metagame comparisons.

The speculative GCD tier list was heavily built on Potential, by necessity of the fact that this emerging meta had yet to be defined. Through tournament placements, most of these potential placements have been justified by performance, including Mal'ady, Gaia, and Ethelhime in S-Tier.

Ethelhime specifically is a list which has had consistently strong power, and strong performance outside of tournament, as well as being specifically effective into both Gaia and Ethelheim. Although her placement has now been justified additionally by performance, her initial placement is still a result of potential and metagame theorizing.