When the Boston Celtics open the Eastern Conference finals Sunday against the Cleveland Cavaliers, Boston will be in a familiar position: Playing as a home underdog in Game 1, and entering a series as a major betting underdog despite being the higher seed. The last time they were in that situation, the Celtics won the game — and, in a result that defied the Vegas odds in a huge way — won the series in five games against the Philadelphia 76ers.
Celtics vs. Cavs Game 1 Odds: Cleveland Is Favored
The Cavaliers, who beat the Celtics in five games in last year’s Eastern Conference finals, opened as 1.5-point favorites against the Celtics in Game 1. Cleveland is a -300 favorite — bet $300 to win $100 — to win the series. Boston is a +240 underdog — bet $100 to win $240 — at the Westgate Las Vegas Superbook.
The Celtics Have Defied the Odds This Postseason
Betting against the Celtics so far this postseason has not been a smart play. Boston beat Philadelphia three times as an underdog — in Games 1, 2 and 3 — and covered the spread in Game 5, the one time they were a narrow favorite. (The Celtics were 1-point favorites; they won 114-112.) A bettor who placed a $100 bet on the Celtics to win the series before it started would have won $325, given that the Celtics were +325 underdogs to win the series.
The Boston-Philadelphia series featured a few other betting oddities: Despite being the higher seed and holding home-court advantage, the Celtics opened as an underdog in all five games. They only ended up as very slight favorites in Game 5 because the line moved in their favor after it opened.
In most cases, betting markets remained bearish on the Celtics despite everything that was transpiring on the court, where Jayson Tatum, Terry Rozier and Co. were making fans temporarily forget about Kyrie Irving, who’s out for the postseason following knee surgery. (Boston’s other mega-star, Gordon Hayward, missed all but the first six minutes of the regular season after breaking his ankle during the season-opener against the Cavs.) In Game 4, Philadelphia opened as a 6-point favorite despite trailing the series 3-0. ESPN Stats and Information — responding to a query from Fivethirtyeight’s Nate Silver — said it was the first time since at least 1991 that a team trailing 0-3 was that heavy a favorite in Game 4. Yet that happened to be the only game in the series that a bettor wagering on the Sixers against the spread would have come out on top. Philly won the game 103-92 and covered the spread with a little bit of room to spare.
Most of the Early Game 1 Action is on the Cavs
With the Cavs series on tap, Vegas remains down on the Celtics. Not only are the Cavs 1.5-point road favorites, but almost all of the early money is on LeBron and Co. to cover the spread, according to the Action Network.
To a large degree, the Cavs have earned that kind of respect from bettors. Though they scuffled through a mediocre regular season and finished fourth in the Eastern Conference, they’ve once again turned it on in the postseason, with LeBron James playing perhaps the best basketball of his career. Home-court advantage is generally a major factor in the NBA playoffs, but James and Co. have demonstrated repeatedly that they can win without it — something they did last year against the Celtics, and in their most recent series this year against the top-seeded Raptors.
Though oddsmakers saw the Toronto-Cleveland series as more evenly matched than Boston-Philadelphia, the Cavs were still a modest underdog — a status that went away after they won Game 1 in Toronto. That Cleveland won the series wasn’t out of line with what handicappers expected. That the series was over in four games was a big surprise.
The Celtics & Cavs Are Both Betting Longshots to Win the Title
Though oddsmakers view the Cavs as pretty heavy favorites to beat the Celtics, oddsmakers don’t give Cleveland all that much of a shot at winning its second title in four years. Westgate lists the Cavs as 5/1 to win the title. Though those odds are a whole lot shorter than the 22/1 odds the Celtics have, they’re considerably behind both teams competing in the Western Conference Finals.
Westgate has the defending champion Warriors as 5/8 favorites to win the title, meaning they have a better than 50-50 shot to do so. The Rockets, who host Golden State in Game 1 on Monday, are at 12/5.