Headline accuracy — 36-deck authoritative core set

The boundary stress-test cohort — 14 community-labeled decks

The core set's strength — every label traceable to an authoritative source — is also its limit: WotC publishes no canonical B1 ("just a theme pile") or B4 ("optimized but not cEDH") decklists, so the core set cannot measure those boundaries. In June 2026 we added a separate cohort of 14 real community decks (sourced from Archidekt with owner-stated bracket labels, re-judged by us against WotC's framework) specifically to probe the B1/B2 and B3/B4 edges — including decks chosen because they are hard calls. These labels are community judgment, not WotC canon, so we report this cohort separately and never blend it into the headline numbers.

Cohort	N	In-range	Within-1	Exact	Power-in-range
Authoritative core	36	36/36 (100%)	36/36 (100%)	35/36 (97.2%)	36/36 (100%)
Boundary cohort (community-labeled)	14	14/14 (100%)	14/14 (100%)	10/14 (71.4%)	14/14 (100%)
All decks	50	50/50 (100%)	50/50 (100%)	45/50 (90%)	50/50 (100%)

Reading the split honestly: the engine stays 100% in-range across all 50 decks, but exact-match drops to 71.4% on the boundary cohort — exactly where it should drop, because those decks were picked for sitting on the framework's fuzzy edges (theme piles that play like Core decks, optimized lists a card short of cEDH). Where engine and community label disagree, the per-deck rows below let you judge for yourself.

Methodology

Reference deck sourcing

Every reference deck has a public source URL. We derive bracket assignments only from authoritative sources:

• WotC official precons — decklists from MTGJSON's canonical deck data, secondary URLs to WotC's announcements. Bracket assignment per WotC's Commander Brackets Beta framework: stock precons without Game Changers fall in B1–B2 (boundary fuzzy by design); stock precons with Game Changers are forced to B3 floor.
• cEDH archetype canonicals — sourced from the cEDH Decklist Database, which curates competitive-tier decks via community submission + curator review. By definition, any cEDH archetype is Bracket 5 per WotC's framework. The decklists are representative archetype lists, not specific tournament copies.

Audit methodology

We cross-checked every precon's mainboard against the bracket calculator's 53-card Game Changers list (stored in /tools/commander-bracket/bracket.js's GAME_CHANGERS constant, mirroring the WotC Feb 2026 update). One precon, AbzanArmor (Tarkir Dragonstorm Commander), contains Seedborn Muse, which is on the GC list. Per WotC's framework, any Game Changer forces a Bracket 3 floor — so AbzanArmor's expected_bracket = 3, not B1. This is documented in the reference data and matches the calculator's verdict.

cEDH provenance chain

Every cEDH reference deck is sourced via a two-link chain: cEDH Decklist Database (community-curated tier list of cEDH archetypes) → linked Moxfield primer (community-vetted decklist for that archetype). We fetched the canonical Moxfield decklist via api2.moxfield.com/v3/decks/all/<id> on 2026-05-06 and confirmed each list is exactly 100 cards. Each row's source ↗ link goes to the human-readable Moxfield primer page; you can verify the decklist is identical to ours.

Pass criteria

For each deck, we record three bracket-accuracy criteria:

• Bracket-in-range — predicted bracket ∈ [expected_bracket_min, expected_bracket_max]. Primary metric. WotC's B1/B2 boundary is intentionally fuzzy, so stock precons get [1,2] range.
• Bracket-±1 — predicted within 1 of expected_bracket midpoint. Secondary metric reported for comparability with industry tools (ScryCheck reports 80% bracket-exact, 92% bracket-±1).
• Bracket-exact — predicted === expected_bracket midpoint. Strictest. Affected by the inherent fuzziness of WotC's framework on stock precons.
• Power-in-range — predicted power level ∈ [expected_power_min, expected_power_max]. Independent check on the engine's continuous output.

Per-bracket accuracy (core set)

Expected	N	In-range	Within-1	Exact	Power-in-range
B2	11	11/11 (100%)	11/11 (100%)	10/11 (91%)	11/11 (100%)
B3	6	6/6 (100%)	6/6 (100%)	6/6 (100%)	6/6 (100%)
B4	3	3/3 (100%)	3/3 (100%)	3/3 (100%)	3/3 (100%)
B5	16	16/16 (100%)	16/16 (100%)	16/16 (100%)	16/16 (100%)

Confusion matrix (core set)

Rows = expected bracket; columns = predicted bracket. Diagonal = exact match.

	Pred B1	Pred B2	Pred B3	Pred B4	Pred B5
Exp B1	0	0	0	0	0
Exp B2	1	10	0	0	0
Exp B3	0	0	6	0	0
Exp B4	0	0	0	3	0
Exp B5	0	0	0	0	16

Per-deck results — authoritative core (36 decks)

Every row links to the deck's source URL. Click "source ↗" to verify decklist + bracket assignment yourself.

Per-deck results — boundary stress-test cohort (14 decks)

Expected brackets in this table are community labels re-judged by us against WotC's framework — not authoritative canon. Source links go to the public Archidekt decklists.

What's next

• Expand the reference set toward 250+ decks. Priority: more cEDH archetypes (B5), more recent precons (B1–B3), authoritatively-tagged B3–B4 decks (community + tournament).
• Add automated CI: re-run validation on every bracket.js change. Keep accuracy honest as the engine evolves.

Browse the full precon library

Beyond this reference set, we've run every recent Commander precon through the same engine. Browse all 61 analyzed precons → — filter by bracket, set, or color identity. Each precon links to a full per-deck analysis with the same passport (bracket, power, Tipping Point) the calculator produces.

The methodology behind the metric

For the long-form story on how the engine produces the Tipping Point chip you see on every analysis — including the WASM Monte Carlo internals, comparison to Frank Karsten's land-count formula, and why no competing bracket calculator can replicate it — read "We Simulated 5 Million Mana Bases. Here's What We Learned About Tipping Points." →

Validation framework: scripts/run-validation.cjs · Reference data: /methodology/reference-decks.json · Calculator source: /tools/commander-bracket/ · Methodology post: how the bracket calculator works