Okay, so...
What you should know is that most places use a simple, external provider on prop bets. DraftKings is exclusively Swish, short for SwishAnalytics. They're pretty much flawed but they're cheap and do the job well enough to be outsourced. There are other sources, like how ESPN Bet is Penn in the overall, who also does The Score and used to do Barstool's numbers. Kambi is a common provider of odds too, and they're usually very easy to beat. DraftKings uses them albeit not for props, but in the US, here's some outs that use their services: 888bet, PARX, Unibet.
The real value secret with such props is to the under, just because of the way the general population thinks:
If a company, DraftKings, is offering a bunch of different prop offerings, the public is going to pick the over, because they want to root for something to happen. So it's ultimately a greater liability to the company as a result. The amount of people who take the unders on these things are a lot smaller, so the price you're getting is far likely to be closer to internal probability, not to mention oftentimes less juice. And that's without touching how you model it. Or pay for a worthwhile, successful service like an Establish the Run, they're pretty amazing.
It bears repeating: Shop your books. There's no reason not to have an odds screen up if this is viable for you in your state, to ensure you get the best price. It sounds small the differences you'd make/gain or lose but it adds up fast over time. It takes that much little effort to be that much more profitable in the long run.
Check out this Wemby play for 3s made tomorrow. Without even taking a stance, look at the difference this makes: If you like his over, you're laying 10 less cents to do the same thing at Pointsbet/Fanatics than you would be at BetMGM. Should that lose, you just saved yourself a little more than 7% of your cost and lay. If you like his under? You got to DraftKings or BetMGM and get five cents more, or 5% more just for shopping with them. It's coupon clipping but with sports bets. If you wagered, say, $100 on this prop and the under hit, that's $5 for doing very little. And $100 is often on the lower end of bets, so you can see why this matters and adds up fast, yeah?
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