Conventional wisdom says NBA teams without stars struggle at the end of games, especially postseason ones when defensive pressure increases. The Philadelphia 76ers test that theory, and so far they are providing evidence in its favor. Game 1 against the Boston Celtics was just the latest tightly-contested match in which the Sixers could not close the goddamn door.

“We’ve done it by committee. It’s ‘move the ball and whoever gets the open shot.’ That’s sort of who we are right now as we try to grow,” Doug Collins described Philadelphia’s late-game mentality. “That’s why we struggled in the regular season. We were 2-18 in games under 90 points. I think we won one game (decided by) three points or less — that was in Indiana in overtime late in the year. We won (only) two games by five.”

The Sixers punched the Celtics straight between the eyes to begin Game 1, and still had a 10-point lead with 10:37 remaining in the fourth quarter. But that was when their lack of late-game execution became highlighted in neon green. As the Celtics surged thanks to the heroics of Kevin Garnett and Rajon Rondo, the Sixers lost themselves.

Yes, the 76ers are athletic and they are skilled and they have waves of versatile perimeter players who can cause teams fits, especially in the open court. But they are also devoid of a natural go-to guy. Asked which Sixer he would not want with the ball with 10 seconds left in a close game, Doc Rivers did not hesitate before replying Lou Williams. But Williams is still young, lacking inexperience in big games and not your typical go-to scorer. At this stage in his career, at least, he has more Jason Terry in him than Dirk Nowitzki, meaning he’s better-suited as a sparkplug off the bench than someone relied upon to carry an offense in crunch-time against a defense designed to limit his good looks.

In the final three minutes of Game 1 alone, Williams got rejected on a fast-break layup, forced a miserable attempt from the corner that even Nate Robinson would have called a bad shot, and turned the ball over while trying to force his dribble down Avery Bradley’s throat. The Sixers hit four field goals during the final nine minutes — one was an Andre Iguodala triple off the dribble, another came when Jrue Holiday hit a 19-foot jumper with one second left on the shot clock, and another came when Spencer Hawes stole the ball in the open court and converted a coast-to-coast layup. In other words, even the rare Philadelphia scores did not come from high-percentage looks.

“We had a great chance to get this game today, and we just had four really bad offensive possessions that really hurt us,” explained Collins. “And that’s sort of the sign of a team that’s trying to grow and figure what it is to play this kind of championship basketball in the NBA playoffs.”

The Celtics aren’t known as a powerful offense either (their 24-ranked offense was seven spots below Philly’s in the regular season), but they know what it’s like to play championship basketball. When contests get close, the Celtics generally have the know-how and ability to run patiently through sets to get a decent look (think: Kevin Garnett’s game-winner in Game 6 against Atlanta). But what some of their big shots disguise is that most of Boston’s late-game heroics come in the form of defense.

Their defense is always stingy, but the Celtics have a way of strangling opponents even more so during a game’s final moments. In six playoff outings against the Hawks, Boston allowed just 108 points for an average of 18 per quarter. In their one overtime affair with the Hawks, the Celtics surrendered only four points during the extra session. The Sixers managed 20 fourth-quarter points in Game 1, but six of those came in the first 1:08, when the Celtics trotted out a strange (and probably not good) lineup that featured Keyon Dooling at point guard and Mickael Pietrus at power forward. After the Celtics subbed in Avery Bradley and Rajon Rondo for Dooling and Pietrus, the Sixers mustered just 12 points in the final nine minutes.

The Celtics and Sixers, in a lot of ways, are evenly matched teams. But when the fourth quarter arrives and buckets become more difficult to come by, several signals indicate that Boston should thrive.