So, the Celtics won again. They have for the last two games looked like what we thought they were heading into the Eastern Conference Finals: the better team. Which begs the question, are we really about to see what we never thought we’d see?
Over the past 40 years (since 1984, when the league expanded the playoffs to 16 teams), 116 squads have trailed 3-0 in a seven-game series. The first 115 of those teams have failed to qualify for the next round. Just 41 of them even pushed the series to a Game 5. Among that group of 41, only 10 (including the Celtics) advanced to a Game 6. And a mere two (1994 Nuggets and 2003 Blazers) of the previous nine such teams forced a Game 7.
In other words, the win rate in subsequent games for teams in a 3-0 hole has started out incredibly low, and gotten progressively lower.
For whatever it’s worth, the FiveThirtyEight RAPTOR-based forecast gives Boston a 53% chance of winning Game 6 in Miami, and then a 71% chance of taking Game 7 at home if it wins that game. That works out to a 37.6% chance to win the series outright, in a situation where the series winning percentage to date is 0.0%.
Basketball-Reference’s Playoff Probabilities feel even better about the Celtics’ odds, pegging them with a 46.5% chance of advancing to the Finals, meaning the Heat are basically coin-flip favorites because they only need to win one of the next two games instead of both of them.
ESPN’s Basketball Power Index actually favors Boston to make the Finals right now, giving the Celtics a 58.9% chance of winning each of the next two games. If that sounds incredibly high, consider that the preseason projection had the Celtics beating the Heat 97% of the time.
The implied probability of a Celtics series win based on Vegas odds (-110 entering Game 6), has now shot all the way up to 47.6%. Damn near a coin flip. That’s up from 30.3% entering Game 5 and 11.1% entering Game 4. Again, the Celtics are in a scenario with a historical 0.0% series win rate to date.
More and more, it seems like there is actually pretty high confidence in the Celtics pulling this off. Less than a week ago, I was on “no fucking way” territory. I’m getting pretty close to “well I kinda think they’re gonna do it” range now. Especially when you consider that the Heat’s two four-game losing streaks during the regular season each immediately followed three-game winning streaks. It’s funny how back-to-back wins will completely change your tune, even if that only gets you halfway there.
Update (10:23 a.m.)
As pointed out by an astute reader, the Celtics don’t have to come back from down 3-0 anymore. They only have to come back from being down 3-2. Which has been done plenty of times.
During the aforementioned period, NBA teams are 35-194 in series where they trailed 3-2, no matter how they got to that point. (We’re only including series played in the 2-3-1-1-1 format here, because getting both Game 6 and Game 7 at home would be a much different situation than the one the Celtics are in now.) That’s an 18.4% win rate, and each of the various projection systems and markets gives the Celtics at least twice as good a chance to win at the moment, likely owing the pre-series expectations that the Celtics are the significantly better team.
Still, if you look at the Games 6 and 7 record of those teams overall, as well as broken down by whether they had originally trailed 3-0, you see a pretty wide divergence.
That is of course subject to small-sample concerns, but it’s notable that the Game 7 winning percentage of non-3-0 trailers (38.5%) is pretty damn close to the percentage chance that FiveThirtyEight gives the Celtics of winning the series (37.6%) at the moment.
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