A grade answers one question about a price: how far is it from fair? It compares a book’s price with Pinnacle’s no-vig price for the same line, and the gap between them, the expected value (EV), decides the letter. It says nothing about who will win.
The scale
Six grades, named like a roster. The EV bands are fixed. The count on each row is how many prices carry that grade on today’s board.
The largest edges on the board. Rare by design, and alerted on their own.
A strong edge, as long as the price is still there when you bet.
Solid, repeatable value. Most of a disciplined season is built here.
A thin edge. Real, but with little room for error in the fair price.
Barely above fair. Inside the noise of the fair price itself.
Below fair. The book keeps the edge.
How a grade is built
Three steps, in this order. The math is the same everywhere on the site, from the Play-by-Play feed to the API.
1. A fair price from Pinnacle
Pinnacle runs thin margins and takes large bets from sharp bettors, so its line is widely treated as the sharpest public estimate of the true probability. We remove its margin, the vig, to get a fair probability for each side. The full method is in No-vig odds.
2. EV for every price
We compare that fair probability with every price on the same line at DraftKings, FanDuel and BetMGM, and each one gets a grade. The best price on each side is the play you see in the feed. Pinnacle is the reference only and is never returned as a play.
3. How much to trust the edge
EV assumes the fair price is right and that the book will still take your bet at its price. Three questions decide how far to believe it:
- Market depth. A main-market price at a book that takes real size is worth more than the same number on a market with low limits, or one about to be pulled.
- How sharp the reference is. The fair price is only as good as Pinnacle’s line. Its margin on that market is a useful tell: the lower it is, the more competitive the price.
- How long the price has held. A gap that opened seconds ago is often a stale quote about to be corrected. One that has survived several Pinnacle updates is more likely to still be there when you place the bet.
- Pinnacle
- Padres +118 → 45.9% · Brewers −130 → 56.5%
- Margin
- 45.9% + 56.5% = 102.4% → 2.4% vig
- Fair
- 45.9% ÷ 102.4% = 44.8% → fair price +123
- DraftKings
- +140 → decimal 2.400
- EV
- 0.448 × 2.400 − 1 = +7.5% ≥ 6.0% → S
On the board this is an S, Franchise play. Note what the inputs are: two Pinnacle prices and one price at your book. Nothing about the teams, the form or the weather.
Bands use the exact EV, not the rounded one. Over 222.5 at DraftKings +103 (76ers vs Celtics) shows +2.5% on the board, but its EV is +2.46%, so it is a C, not a B.
Today’s board
Grades are counted over every open price at DraftKings, FanDuel and BetMGM that sits on the same line as Pinnacle: 1,196 of them on today’s illustrative board.
93.9% of prices are F. That is the vig doing its job: a book that charges a margin on both sides leaves most of its lines below fair. Of the 73 prices that beat fair, 58 (79%) are B or C, and the busiest bin is 1.0–1.5%. Edges of 6% or more are rare: 4 today. When you see an S, the right first question is why the price is still there.
Arbs, middles and steam are events, not grades
The board flags three other kinds of event. They get their own tiles because none of them is measured against a fair price.
1/decA + 1/decB < 1. Split the stake in the right ratio and the return is the same whichever side wins, as long as both bets stand. Measured by margin: the best today is +1.65%.Steam can leave a soft book behind: in 4 of today’s 10 moves, at least one book has not caught up yet. That stale price is graded like any other play. From today’s Padres vs Brewers market: Pinnacle moved +130 → +118 in 4 min. DraftKings still dealing +140, now an S-grade play. More in Line movement. Arbitrage unlocks with Varsity; middles and steam with All-Pro.
What each league sees
Every league gets the same math and the same grades. What changes is which grades you can open.
Plays above your league are not hidden. They stay on the board with the grade tile visible and the pick, book, price and EV blurred behind a lock. Counts stay visible too: a Rookie or Varsity player can see that 4 S-grade prices are live today without seeing which ones.
XP, drills and standings run on the same rules in every league. Compare the leagues on Pricing.
Grades and stake size
A grade measures the price. It does not tell you how much to stake. Guru-frat suggests a quarter of the Kelly stake: full Kelly assumes the fair price is exactly right, and a quarter of it leaves room for being wrong. With an edge, the formula simplifies:
Because dec − 1 sits in the denominator, the same edge earns a smaller stake at longer odds. Two plays from today’s board:
The B-grade favorite earns about 2.3× the stake of the S-grade underdog. Kelly already weighs the edge against the odds, so never size up because the letter is better.
A player with a $2,500 bankroll, a $50 unit and a 5-unit daily limit has used 4 units today and is looking at Padres ML at DraftKings +140.
Kelly fits inside what is left today, so Kelly sets the stake. Any play where ¼ Kelly is above 2.0% of the bankroll would be capped at the $50 left. With the limit used up, the answer is zero, whatever the grade. The Game Center runs the same Stake check on every game.
Grades touch XP in exactly one place: drafting a B or better earns +20 XP. Stake size, bet count and winning never earn XP.