Read the metagame and use statistics carefully
Deck stats can help you make choices. Check which players, decks, and patch the numbers describe.
What is the meta?
The metagame, or meta, is the mix of decks people play and how those decks do against each other.
It can change by rank, region, time, and patch. Your last few opponents may not match a large report's group of players.
Before using stats, check the patch, dates, game count, ranks, exact list, and matchups. A high win rate from a few games can change a lot. Old patch data may no longer fit.
Different stats answer different questions
Overall win rate shows results against the opponents in that sample. Matchup rates show which decks caused those results.
Mulligan stats help with starting-hand choices. Drawn and played win rates need care. They depend on when a card can be used and when players choose to use it.
A finisher may have a high played win rate because people use it just before winning. A defense may have a low rate because people need it when far behind. Neither number alone proves a card is good or bad.
Special answers have a cost
A tech card is a narrow answer to a certain problem. It may help one matchup and weaken your usual plan.
Ask how often that opponent appears, how much the card helps, and what card you must remove. One upsetting loss is a reason to look closer, not proof you need a change.
Keep claims fair
After a patch, call early ideas early ideas. Wait for enough useful games before treating them as firm advice. Use data to ask better questions and review plays. No deck ranking lasts forever.