With his Toronto Raptors facing elimination and the daunting task of coming back from a 3-0 deficit in their first-round series against the Philadelphia 76ers, coach Nick Nurse made the case for his team to accomplish something no team in NBA history has done.

“I think it’s a heckuva challenge, and somebody’s got to do it,” Nurse told reporters last week. “If it gets to 3-1, it’s not 3-0 anymore. And 3-1’s been done.”

The NBA is an outlier. Four NHL teams have rallied from down 3-0, most recently the Los Angeles Kings en route to the 2014 Stanley Cup, while MLB’s Boston Red Sox famously completed a comeback from down 3-0 to the rival New York Yankees in the 2004 American League Championship Series as they won their first World Series title since 1918.

Two wins later, Toronto is one victory at home (Thursday, 7 pm ET, NBA TV) from becoming the first team since the 2003 Portland Trail Blazers to even reach Game 7 after going down 3-0.

Whether the Raptors complete the historic turnaround or not, the scare they’ve put in the Sixers is the latest indication it’s only a matter of time.

Let’s examine why no NBA team has overcome a 3-0 deficit and one reason the Raptors could become the first.

The history of teams down 3-0

Before this season, 143 teams in NBA history had fallen behind 3-0 in a best-of-seven series. Add the Brooklyn Nets, whose first-round matchup against the Boston Celtics ended in a four-game sweep, and teams facing this deficit are 0-144 all-time.

Maintaining belief doesn’t seem to be the primary issue. Teams frequently rally to win Game 4, typically at home, and avoid a sweep. (Just 22 of the 146 teams to go down 3-0 had home-court advantage in the series.) Including this year’s games, this group has collectively gone 56-90 in Game 4 for a .384 winning percentage.

Under the NBA’s usual best-of-seven format, avoiding a sweep means heading back on the road for Game 5, and that’s where the comeback often ends. The Denver Nuggets’ loss Wednesday brought teams down 3-0 to 14-42 (.250) when they reach Game 5, meaning less than 10% of teams in that situation even get to a sixth game in the series.

Countering the notion that pressure shifts over time to the team unable to close out, the winning percentage for teams down 3-0 declines again in Game 6. Despite having won the previous two games to stave off elimination, they’ve gone 3-10 (.231) in Game 6. And as you already know, all three teams that won three straight to force a Game 7 (the aforementioned 2003 Blazers, 1994 Nuggets and 1951 New York Knicks) lost that game.

The math against teams down 3-0

In theory, coming back from a 3-0 deficit doesn’t seem much harder to pull off than the comebacks from 3-1 deficits that are common. (There have been five of them since 2015, including the Nuggets pulling off back-to-back 3-1 comebacks in the 2020 bubble playoffs.) For that matter, it’s also seemingly not so different from going 2-0 in a series and rallying to win the next four games, something that happened twice in last year’s playoffs — the LA Clippers against the Utah Jazz in the second round and the Milwaukee Bucks in the NBA Finals against the Phoenix Suns.

Part of the difference lies in home-court advantage. By definition, a team down 3-0 must win at least two games on the road, usually including a deciding Game 7 in which home court offers an even greater edge. (Historically, home teams are 109-33 in Game 7s, though the home win percentage has declined slightly to 71% in the 2000s.)

In contrast, a higher seed down 3-1 or a lower seed down 2-0 can come back with only a single road win. Only the 2016 Cleveland Cavaliers (against the Golden State Warriors in the 2016 NBA Finals) in the past 25 years have rallied from 3-1 by winning twice on the road. At the extreme, the Nuggets’ bubble turnarounds didn’t require navigating any road games in a neutral setting.

The other factor that makes a 3-0 comeback much less likely is that the gap between the two teams is typically larger. Teams down 3-1 have won 38% of their games the rest of the series, as compared to just 34% for teams down 3-0.

Still, over nearly 150 series it’s something of a surprise that we’ve never seen a 3-0 comeback.

How a 3-0 comeback might happen

When we eventually see a team come back from down 3-0 in a series, odds are health will be a factor. Consider the way the 2016 Warriors wore down over the course of the NBA Finals against the Cavaliers, with Andrew Bogut sidelined for the final two games of the series after Draymond Green missed Game 5 due to a suspension.

It’s possible we could have seen a 3-0 comeback earlier that same postseason had the Trail Blazers not won Game 3 of their first-round series with the LA Clippers. Even after dropping that game in Portland, the Clippers were heavy favorites to advance until both Blake Griffin and Chris Paul went down with series-ending injuries during Game 4. The Blazers won the remaining three games of the series against a depleted Clippers team and would have had a strong chance to win had they gone down 3-0.

As I noted last year, injuries have never been more common during the playoffs than they are now. The four years since 1978 with the most playoff games lost to injury by rotation regulars have all come in the past seven postseasons.

The Philadelphia-Toronto series has been shaped by injuries on both sides. The Raptors got few contributions early in the series from Gary Trent Jr. (non-COVID illness) and Thaddeus Young (left thumb hyperextension) and saw Rookie of the Year Scottie Barnes miss Games 2 and 3 with an ankle sprain suffered in the opener. With those three players operating at closer to full strength, Toronto has overcome Fred VanVleet missing the past game and a half due to a hip flexor strain. The Raptors have listed VanVleet as doubtful for Game 6.

Meanwhile, Sixers star Joel Embiid is dealing with a ligament tear in his right thumb that he suffered in Game 3. Although the injury didn’t stop Embiid from draining the winning 3-pointer late in that game, he has been limited to 41 points on 14-of-31 shooting in Philadelphia’s past two losses.

Dating back to Game 3, Toronto has outscored the Sixers by a combined 20 points. Only one team down 3-0 that has rallied to force a Game 6 has done better over the same span: the 2007 Chicago Bulls against the Detroit Pistons. Detroit still won Game 6 in Chicago to end the series.

The 76ers might well squelch any notion of the Raptors making history with a win Thursday in Toronto. Eventually, however, it’s inevitable that some team is going to come back from a 3-0 deficit and make history in the process.