Requirement: kickers and defenses are still overvalued. This doc specifies the fix and the research behind it. Implementation is phase v2.2. Companion:
VALUE_ENGINE.md.
External consensus and our own league context agree:
- K and D/ST have the highest week-to-week and year-to-year variance and the lowest predictability of any position. The top-10 at both positions turns over almost completely year to year. (Fantasy Points, FantasyPros VORP)
- Because they're freely streamable off waivers, their true value over replacement collapses — the replacement-level K/DEF is nearly as good in expectation as the "elite" one. Accepted practice: draft them last, stream all season.
- Projection models overestimate busts and underestimate booms, and TD/turnover-dependent scoring (exactly what K/DEF are) is the most variable. A point projection treats a volatile D/ST like a stable WR — that's the bug. (ParlaySavant, FF Analytics)
Diagnosis: v1 ranks K/DEF on projected point total with a per-position replacement baseline that's too generous. It rewards a high mean without penalizing (a) low predictability and (b) the trivially-available replacement. So elite-projected K/DEF float up the board.
Each player gets a predictability score ρ ∈ [0,1] from the Projector: how
reproducible is this projection? Derived from historical year-over-year rank stability for the
position + this player's own variance + share of points from high-variance sources (TDs,
turnovers, return/defensive TDs). Value is discounted toward replacement by low predictability:
adj_value = replacement + (raw_VORP) * f(ρ) # f(ρ) ≈ ρ^k, k tuned by backtest
K and D/ST have structurally low ρ → their VORP is heavily compressed toward 0. Stable
RB/WR/QB keep most of their VORP. This is position-agnostic — it just happens to hit
K/DEF hardest because the data says it should.
Set K/DEF replacement at streamer level, not "12th-best." Because every team streams, the realistically-available K/DEF each week is close to the positional median, not the worst starter. Concretely: replacement baseline = the expected points of a matchup-optimized streamer (top-of-waiver each week), which sits near the position's upper-middle — crushing the gap between "elite" and "replacement."
Our league has distance-based kicker scoring (50+ = 5, 60+ = 6) and a yardage-allowed
D/ST component (uncommon) — so some differentiation is real: kickers with big legs / on
high-scoring offenses, and genuinely stout low-yardage defenses do carry more value. The
model keeps a KickerProjector/DefenseProjector that captures this, but the predictability
discount + streamer replacement bound how high it can lift them. Net effect: the best
K/DEF are a modest edge, not a mid-round pick.
| Pos | Replacement basis | Predictability ρ | Net v2 effect |
|---|---|---|---|
| QB | league slot demand (superflex ⇒ ~24th) | high | unchanged (correctly premium) |
| RB/WR | slot demand incl. FLEX/OP | med–high | unchanged |
| TE | slot demand | medium | unchanged |
| K | weekly streamer (≈ upper-median) | low | strongly compressed |
| D/ST | weekly streamer (≈ upper-median), bounded by yardage signal | low | strongly compressed |
- Backtest 2021–2025 (shared harness with
DRAFT_LOGIC.md): does v2 value, used to draft, beat v1 value on season points-for, and stop spending early picks on K/DEF? - Calibration check: do realized boom/bust frequencies match the emitted distributions (reliability diagram)? Especially for K/DEF.
- Sanity: no K or D/ST should rank above a startable offensive player in superflex draft value except in extreme, well-justified cases.
- K/DEF draft value compressed to "last few rounds" range across 2021–2025 backtests.
- Predictability score surfaced in the UI (the player-card "predictability meter") so the why is legible.
- No regression to QB/RB/WR/TE valuations vs. v1 on backtest.