Sonar Sweep Protocol: Blind Defense Analysis Tools (2026)

Blind defense is not a personality test—it is a pattern on a sonar screen. You will not fix BB leaks by memorizing one chart; you fix them by sweeping your database for where chips leave your stack out of position. This article is about analysis tools and filter workflows, not a spot quiz. If you want interactive blind-defense drills, use a range trainer separately.

What Sonar Actually Measures

Signal	Software source	Healthy direction
BB VPIP vs BTN open	PT4/HM3 filter: Hero BB, Villain BTN raise	Defend enough to avoid over-folding; not so wide that postflop spew dominates
Fold to steal (SB/BB)	PokerCraft positional stats, HUD-free rooms	Extreme high fold → bleed; extreme low → postflop disaster
BB BB/100 by opener position	Tier-A positional reports	Worst vs BTN/SB first in queue
3-bet defense vs open	Filter: faced raise, hero 3-bet or call	Cold-call frequency vs 3-bet frequency imbalance

GGPoker official guidance places VPIP in a 22–28% band and 3-bet around 6–10% for 6-max self-check—not blind-specific, but BB numbers that diverge wildly from table average flag a sweep.

Tool Bench for Blind Defense Study

Tool	Blind-defense strength	Limit
PokerTracker 4 / HM3	Custom filters: position, action, stack, pot type; BB/100 splits	Needs HH import; anonymized GG names
PokerCraft	Free positional dashboard, replayer, Hand Moments	No cross-site; rake excluded from profit
Leak Buster 3	Ranks blind-defense EV loss; drill mode	Requires PT4/HM3 database
Range trainers (BBZ, Oracle, etc.)	Preflop defend grids vs open size	Preflop only—pair with HH filters for postflop
MassBuster / pool tools	Population fold/overfold vs steal	Pool data, not your personal leak

Workflow principle: Tier-A filter → flag street → replayer → one rule change. Not: watch a solver video → hope.

Four-Layer Sonar Sweep

Layer 1 — Frequency ping

Filter last 5k–20k hands: Hero in BB, faced single raise, no squeeze.

Record:

• Defend rate (call + 3-bet) vs BTN 2.2–2.5x
• Defend rate vs SB complete/open
• 3-bet % vs call % split

Compare to MDF baseline for pot odds: if villain opens 2.5bb and you must call 1.5bb more, pot is roughly 5.5bb before call → MDF ≈ 5.5 ÷ (5.5 + 1.5) ≈ 79% of continuing combos in theory—not 79% of all 1326 hands. Software shows your actual continue frequency; large gap below MDF on dry steal lines → over-folding leak.

Layer 2 — Range composition

Export or tag defended hands. Sort by hand class:

• Suited connectors / suited aces — high realization OOP
• Offsuit broadways — often over-defended by beginners
• Dominated offsuit (K8o, Q7o) — classic BB bleed

Range trainers show solver preflop grids; your database shows what you actually defended. Gold cells in trainers mean nothing if Layer 1 frequency is wrong.

Layer 3 — Postflop echo

Filter defended BB pots that saw flop. Split:

• Check-fold to c-bet %
• Check-raise frequency
• Call flop, fold turn (the "float then surrender" leak)

PokerCraft replayer + street notes beat raw stats when sample is small. Tag ten losing BB pots per week—pattern appears fast.

Layer 4 — Sizing response

Same filter, add villain c-bet size bucket: ≤33% pot, 50–75%, ≥100%.

Over-folding vs small c-bets is a software-visible leak. Under-check-raising vs large polar bets on dry boards leaves EV on table. No solver percentage needed—compare your fold line to pot odds per bucket.

Worked Filter Recipe (PT4/HM3 Style)

1. Hero position = BB
2. Preflop: faced raise, one caller max (SRP focus first)
3. Villain position = BTN (repeat for SB, CO)
4. Stack depth 80–120bb (adjust for your game)
5. Sort by amount won/lost
6. Replay top 10 losers—not winners

Ask each hand: Was preflop continue correct at this price? If yes, postflop line is the leak. If no, fix range before studying turn strategy.

MDF Sanity Check (No Fake Solver Lines)

When facing a c-bet after defending:

• MDF = pot ÷ (pot + bet)
• Example: pot $40, bet $20 → MDF = 40/60 ≈ 67% of range continues

Use MDF as a defense budget, not a mandate to call every gutshot. Software tells you whether you mass-fold below budget (exploitable) or mass-call above it (postflop bleed).

Weekly 45-Minute Drill

Minute block	Task
0–10	Run Layer 1 filter; write defend % vs BTN
10–25	Replay five biggest BB losers from filter
25–35	Open range trainer: BB vs BTN 2.5x at your depth; fix preflop gaps
35–45	Pick one rule: e.g., "fold K8o–Q8o vs BTN at NL50" or "check-raise more vs 33% c-bet on A-high dry"

One rule per week beats ten solver trees.

Common Tool Mistakes

• Studying ranges before measuring frequency — pretty chart, same leak.
• Only reviewing hero calls that won — confirms bias, not edge.
• Ignoring SB vs BB difference — SB defense has different pot odds and 3-bet dynamics; filter separately.
• Chasing population stats without HH — pool tools inform exploits; personal filters fix your graph.

Blind defense analysis tools turn BB from a money pit into a scannable signal. Run the four layers monthly; let frequency lead, ranges follow, postflop refine. The sonar ping you want is not "I feel tight"—it is a filter result you can screenshot and compare next month.