🧪Lab Notes #9 — Bottom-Up EV: When You Build Your Own Reality

“If you disagree with the market, you’d better have a reason — and receipts.”

Top-down EV teaches you how to listen.

Bottom-up EV teaches you when — and how — to talk back.

This is where betting stops being shopping and starts being construction.

And it’s where a lot of smart people learn humility the hard way.

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🧠 Why Bottom-Up EV Exists at All

If markets were perfectly efficient, bottom-up EV wouldn’t exist.

But they’re not.

Some markets are thin.
Some information moves slowly.
Some details don’t matter to the crowd — until suddenly they matter a lot.

Bottom-up EV exists for one simple reason:

Sometimes the market hasn’t finished building the number yet.

So you step in and do it yourself.

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🧠 Bottom-Up EV: Build Your Own Number

Bottom-up EV is the DIY route.

You don’t start with the sportsbook’s price.
You start with your own projection — then see if the book agrees.

This means:

1. You model the game

2. You arrive at a number

3. You translate that number into probability

4. Then you look at the odds

This is the moment you stop reacting…
and start taking responsibility.

You’re not betting numbers anymore.

You’re making them.

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🧮 A Simple Math Example (Before Things Get Messy)

Let’s keep this friendly.

You model a pitcher for 6.7 strikeouts tonight.
The sportsbook line is 5.5 (-110).

The book is pricing the Over like it wins about 52.4% of the time.

Your model says:

• Over hits 62% of the time

Run the math:

• Win side: 0.62 × $90.91 = $56.36

• Loss side: 0.38 × $100 = $38.00

EV = +$18.36

That’s an 18% edge.

This is usually the moment someone leans back in their chair and thinks,
“Oh wow… I figured it out.”

That feeling is normal.

It’s also dangerous.

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⚠️ Why Bottom-Up EV Is Harder Than It Looks

Because when bottom-up EV fails, there’s no one else to blame.

You didn’t just place the bet —
you designed it.

That means:

• finding the right data

• cleaning it correctly

• choosing inputs that actually matter

• weighting them honestly

• updating as the season evolves

Miss one step, and everything downstream suffers.

Building a model is like designing your own house.

One bad measurement and the roof caves in.
Suddenly you’re not just broke — you’re sleeping in a soggy Fyre Festival tent, asking yourself how confidence turned into disaster so fast.

Everyone who does bottom-up seriously has been there.

The ones who survive learn from it.

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🏒 What Bottom-Up Looks Like in the Real World

Let’s make this concrete.

🏒 Hockey — Shot Props

In the Prop Lab, a hockey shot model doesn’t start with the player.

It starts with the game environment.

You’re looking at:

• pace

• shot volume

• offensive-zone time

• opponent structure

• line role and ice time

• power-play access

You’re not asking,
“Is this guy good?”

You’re asking,
“How many shots does this game realistically allow him to touch?”

If the environment supports 8–9 attempts and the book is pricing him like he gets 5–6, that’s bottom-up EV.

Quiet.
Unsexy.
Powerful.

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🏀 Basketball — Points or PRA Props

Basketball works the same way.

You don’t start with season averages.
You start with opportunity.

You model:

• minutes

• usage

• pace

• matchup pressure

• lineup context

• game script

If a player is stepping into:

• 36 minutes

• elevated usage

• faster pace

• softer defense

…and the book is still pricing him like it’s a normal Tuesday rotation?

That’s bottom-up EV.

Not prediction.

Access.
Opportunity.
Reality.

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🎲 Why Bottom-Up Feels So Personal

Because it is personal.

You built it.

When it wins, you feel sharp.
When it loses, it stings a little more.

Bad bottom-up bettors defend their models.

Good ones get curious.

They ask:

• What assumption broke?

• What changed late?

• What did I overweight?

• What did I miss entirely?

Bottom-up EV doesn’t reward ego.

It rewards honesty and iteration.

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⚖️ Bottom-Up vs the Market

Here’s the rule we live by in the Lab:

If your number disagrees with the market, one of you is wrong.

Sometimes it’s the market.

Often… it’s you.

Your job isn’t to assume you’re smarter.
It’s to calmly explain why the market might be blind here.

If you can’t explain that in one clean sentence, you don’t have an edge.

You have a vibe.

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🧪 Why the Prop Laboratory Exists

Bottom-up EV is powerful.

It’s also unforgiving.

The Prop Laboratory exists to:

• add structure

• enforce discipline

• gate assumptions

• and keep Dr. Seuss away from the blueprints

We don’t build vibes.

We build systems that survive bad nights.

L.S. signing off ⚗️

Jared
Lead Scientist — The Prop Laboratory

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🧪 Coming Up Next

You can do everything right and still lose.

That’s not a contradiction.
That’s variance.

In the next Lab, we tackle the part no one prepares you for:

📊 Lab Notes #10 — Why +EV Bets Still Lose (and Keep Losing)

Because variance doesn’t test your math.
It tests your patience.

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🧪 Lab Glossary: Key Terms from This Lesson

Projection
A data-driven estimate of what a player or team is expected to produce, built from inputs like role, minutes, pace, matchup, and environment — not from recent box scores alone.

Assumption
A belief built into a model about how the game will behave (minutes, usage, role stability, health). Bottom-up EV lives or dies on whether these assumptions hold.

Usage Window
The realistic range of opportunities a player has to accumulate stats, determined by role, game script, and how often the offense actually flows through them.

Model Drift
The gradual loss of accuracy that occurs when a model isn’t updated as roles, rotations, or team tendencies change over the season.

Spreadsheet Confidence
The sudden and unjustified belief that a bet must be correct because it came from a spreadsheet — usually followed by defending the model instead of questioning the assumptions.

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📘 View the Full Master Glossary
💡 Click here to open The Prop Laboratory Master Glossary
(An evolving index of every term, example, and concept across all Lab Notes & Field Studies — updated as the series grows.)

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⚗️ Foundational Labs (1–8)

Lab Notes #1 — Favourites, Underdogs & The Secret Life of Odds

Lab Notes #2 — Implied Probability: The Hidden Math Behind Odds

Lab Notes #3 — The Vig: The Tax You Didn’t Know You Were Paying

Lab Notes #4 — Line Movement: When the Numbers Start Talking

Lab Notes #5 — The Big 3 Betting Markets: Easy to Understand, Brutal to Beat

Lab Notes #6 — Prop Markets: The Side Door To The Sportsbook

Lab Notes #7 — Expected Value: It Isn’t Predicting. It’s Pricing

Lab Notes #8 — How the Market Thinks: Top-Down EV

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