15 and counting, the Celtics are off to the best start in franchise history through 17 games. Boston is getting W’s on the court and at the ticket window.

The C’s (14-2-1 ATS) are the most profitable team against-the-spread to start 2017.

On Monday night, Boston will try to extend its winning streak to 16 games. Brad Stevens’ team is a 7.5-point favorite on the road in Dallas. Recreational bettors expect the good times to continue. At the time of publication, 75% of spread tickets are backing the league’s best team.

Boston keeps defying the odds but here are two trends that point to fading the Celtics.

ATS Regression

Kyrie Irving and the Celtics have covered the spread in 87.5% of their games. That is unsustainable. No team in our database has managed to cash tickets at better than an 80.0% rate past the 39th game of the season.

Teams that are covering the spread in 80% or more of their games have gone 284-315-14 (47.4%) ATS in their next game. If the team is getting 50% or more of spread bets (and the Celtics are): 163-217-9 (42.9%) ATS.

Great Teams vs. Bad Teams

Buy on good news, sell on bad news. That is a simple betting philosophy that pays dividends. The Celtics have the best-record in the NBA, the Mavs the worst. Great teams are overvalued when they play bad teams.

Great teams that have won 80% or more of their games are just 73-112-4 (39.5%) ATS vs. the worst teams, squads that have won less than 20% of games that season, in the Association.

We know the public is wagering on the Celtics, so do the oddsmakers. The books are shading the line because casual fans will lay the points. Contrarian bettors can profit by taking the Mavs and an inflated number.

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