NBA Finals Preview: Why There’s Betting Value On Celtics To Top Warriors

The Golden State Warriors are back in the NBA Finals for the sixth time in eight seasons after missing the postseason each of the last two years. The Boston Celtics' young core of Jayson Tatum, Jaylen Brown and Marcus Smart finally broke through and is now making its first Finals appearance. 

It?s the series everyone wanted -- once the conference finals were set --and it should be great basketball. But we're not here for narratives. We're here to bet, so let's get started with our NBA Finals preview.

The basketball
Any analysis of a series involving the Celtics begins and ends with their defensive prowess. They have allowed just 106.0 points per 100 possessions in non-garbage time minutes this postseason, the second-best defensive rating behind only the Bucks (who played just 12 games). The Celtics' +7.4 net rating in non-garbage time is the best in these playoffs, 2.1 points ahead of the Warriors, who rank second. The Celtics' perimeter defense has been incredible, allowing the lowest frequency of wide-open 3-point attempts this postseason (14.6%) while limiting opponents to 32.2% on 3-point shots overall. Their switch-heavy style of defense is a big reason why they limit open looks from deep, and that matches up extremely well with the Warriors.

The Warriors don't run traditional pick-and-rolls but thrive by using dribble handoffs and off-ball actions to get open looks. They led the league by a wide margin in frequency of off-ball screens during the regular season (9.7%) and postseason (7.1%), and they're averaging 1.07 points per possession when the play runs through an off-ball screen in these playoffs. They're also running the second-highest frequency of handoffs this postseason behind only the Heat, and they have averaged 0.92 points per possession on those plays. 

The Celtics are built for defending those actions. In the postseason, they have allowed just 0.85 points per possession on off-ball screens and 0.80 points per possession on handoffs. Their ability to switch to multiple matchups is a big reason why they're able to defend those actions so well, and against the Warriors they can switch while maintaining a size advantage in almost every matchup.

The Warriors are great defensively as well, and the way they defend will bring some intrigue to this series. They have been brilliant in deterring shots within four feet of the basket this postseason, as only 18.0% of opponents' attempts have been in the restricted area. That rate is insanely low -- some of that is due to the philosophy of their playoff opponents, who were much more perimeter-oriented -- but they also led the league in that category in the regular season (27.0%). 

The Celtics don't pound it in the paint, but 30.3% of their attempts in these playoffs have come at the rim, and they average 19.2 paint touches per game. When the Celtics pressure the paint, their main mission is to kick it out to open shooters. They're averaging 25.3 catch-and-shoot 3-point attempts this postseason, and while they shoot only 36.8% on those shots, that volume is fourth-highest among playoff teams. 

The Warriors' ability to cut off the paint will go a long way toward limiting those catch-and-shoot opportunities, but it's far from the only thing the Warriors have up their sleeve on the defensive end. The Celtics will see plenty of zone defense and other exotic looks.

The betting
Before the conference finals began, Westgate SuperBook oddsmaker Jeff Sherman posted series prices for potential Finals matchups. At that point, he made the Warriors a -120 favorite over the Celtics, and I was of the mindset that the Celtics should be favored in a series against the Warriors, despite not having home-court advantage, as they were over the Heat. However, as the Heat-Celtics series dragged out, my stance softened and given how impactful home court has been this postseason -- worth 3.5 points by my calculations -- the Warriors are deserved favorites against the Celtics.

The question then becomes, by how much? The highest price this series has reached is  -165, which carries an implied probability of 62.3%, and that's too high by my measure. We have seen the market correct itself somewhat, and the consensus right now is -150 (60.0%), which is a fairer price but still a shade higher than the one I expected, which was about -130 (56.5%). Thus, there is some value in betting the Celtics at +130 or better.

As far as betting goes on a game-to-game basis, if we?re going to see this series priced as it is, with the Celtics catching 3.5 points on the road, I believe there's some spread value on the Celtics as well. As previously mentioned, the value of playing at home comes out to 3.5 points by my calculations. The average net rating of a home team in non-garbage time, according to Cleaning The Glass, is +4.8. So the middle ground is between those two numbers. 

The Warriors are 9-0 SU/7-2 ATS with a +16.6 net rating at home this postseason, so one might think home court should hold serve and be worth even more. The problem with that idea is the Warriors' opponent. The Celtics have been incredible on the road this postseason, going 7-2 SU/7-1-1 ATS with the best non-garbage time net rating away from home (+7.2). They covered 66.2% of their regular-season road games as well, so the sample size is there. 

Game-by-game philosophy: I believe there's some spread value on the Celtics as 3.5-point road underdogs and will be betting that angle accordingly.

Finals pick: Celtics win series 4-2

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