The Boston Celtics didn't look great for much of their Game 4 action against the Philadelphia 76ers. But they finally flipped the switch in the fourth quarter, and seemed set to leave Philly with a 3-1 series lead. Instead, they threw away a five-point lead with two minutes left in the fourth, watched James Harden hit another go-ahead three in overtime, and failed to get a shot off on the final possession of the game.

Just when you think the Celtics have figured out how to close out late-game situations, they manage to find an even more crushing way to lose. We saw the same thing happen in Game 5 against the Atlanta Hawks in their first-round series, and even earlier in this series when they fell apart down the stretch in Game 1 to let the Sixers take an early 1-0 lead in the series.

For all intents and purposes, the Celtics could probably have swept the 76ers out of the playoffs already, but instead, the series is knotted at two apiece, and it's now a best of three series. Make no mistake, Boston should win this series, but it's becoming increasingly difficult to be confident in their Finals hopes given the continued poor coaching from Joe Mazzulla.

Joe Mazzulla's poor decision making is killing the Celtics

This isn't the first time that Joe Mazzulla has come under fire for his poor decisions, and based on how things have gone in his first season leading the way in Boston, it likely won't be the last time either. There was a lot that went wrong for Boston in Game 4, and pretty much all of that can be traced back to Mazzulla, which isn't a good thing.

First, we'd be remiss to not mention that, for a point in time in the fourth quarter, Boston completely figured out the Sixers. They had erased a nine-point deficit to take a five-point lead in a span of ten minutes of game action by playing lights out defense, moving the ball on offense to create open looks, and outhustling Philly for literally everything. And yet, they still couldn't carry that momentum to the finish line and win this game.

Everyone will complain about Mazzulla's timeout decisions (and we certainly will in a second) but the first big mistake made in this game from Mazzulla came when he opted to take Jaylen Brown off of James Harden on defense in the first half. Brown picked up a pair of early fouls in the first quarter, and while it made sense to take him off of Harden for a few possessions, there was no reason to totally change the team's defensive matchups because of this.

Harden had 15 of his 42 points in the second quarter, and on all but one of those scoring plays, Malcolm Brogdon his primary defender. Brogdon is a good defender, but the only guy who is playing against the Harden-Joel Embiid pick-and-roll correctly is Brown. Brown is hounding Harden with a three-quarters press, and fighting over screens to allow Boston's big man (usually Al Horford) to play drop coverage as Harden turns the corner.

Brogdon wasn't able to accomplish this, and it resulted in Harden torching the C's throughout the game. He would either step back for a three, where he shot 6-9 from in this game, or get a switch onto Horford for easy buckets. Brown was also on the floor during this time, making it an even more awful decision from Mazzulla, and moving forward, it should be very, very clear Boston cannot afford to have anyone other than Brown guarding Harden.

Brown started this game off on fire for the Celtics on offense, scoring 12 points in the first quarter, but he only finished the game with 21, which was another frustrating development. Philadelphia actually switched their defensive assignments around, sticking P.J. Tucker on Brown rather than Jayson Tatum (who was awful in the first half), and again, Mazzulla couldn't properly identify this.

Tatum had advantageous matchups all game long, but he only began taking advantage of them in the second half, when he scored 22 of his 24 points. De'Anthony Melton is a solid defender, but he has no business guarding Tatum. With Tucker on Brown, Tatum was getting pretty much every matchup he wanted in the second half, and while there's no problem with that, this should have been recognized in the first half, where Tatum spent most of his time aimlessly settling for low-percentage jumpers.

Then, of course, we have the late-decision timeout miscues from Joe Mazzulla. To be honest, the decision to not call a timeout at the end of the fourth quarter is one that the Celtics can live with. Mazzulla prevented Philly from making any substitutions to defend the final play, and assuming you don't make a catastrophic mistake, you are playing for overtime at the worst. Obviously, you don't really want Marcus Smart to be the guy shooting the potential game-winner, but it's a wide open three that he should hit, so you can't truly complain about that sequence.

The real problem came at the end of overtime. Leaving Harden wide open in the corner to double Embiid was an awful decision from Brown, but the Celtics still had a ton of time left to do something to take the lead back. Harden hit his shot with 19 seconds left in the game, but once again Mazzulla opted not to call a timeout.

This is a much worse decision than the previous one at the end of the fourth. Again, preventing Philadelphia from making substitutions and trusting your players sounds great in concept, but the stakes are significantly higher in this situation. Whereas you are tied in the fourth, the C's were down by one in overtime. If you do the same exact thing you did in the fourth, you lose the game.

Turns out, that's exactly what Boston did. They didn't get into their offensive action until there were five seconds left on the clock. Tatum once again generated a wide-open three for Smart, which he ironically ended up hitting, but he didn't get it off before time expired, and Boston ended up losing by one.

Mazzulla should have diagnosed something was wrong early in this possession, and called a timeout to draw up some sort of play. Realistically, Boston should have pushed the ball quickly and tried to get a quick make to extend the game, but that went out the door pretty quickly. But Mazzulla stubbornly believed in his players and liked their matchups, only to watch it once again blow up in his face.

This is careless coaching from Mazzulla, and if this keeps up, the Celtics aren't going to be able to survive much longer in the playoffs. Losses happen in the postseason, but at this point, three of the C's four losses to this point have largely been their own fault. And while he can't go out and hit shots for his team, that falls on Joe Mazzulla's shoulders, and he needs to be smarter moving forward if the Celtics truly intend on winning it all this season.