Here’s how the Celtics’ defense shut down LeBron James and the Cavaliers

If the Boston Celtics did not score in the second quarter of their 25-point win over the Cleveland Cavaliers in Game 1, they still would have held a lead entering halftime. That’s how dominant a defensive performance this Boston team put out, and to be 100 percent honest, it’s nothing remotely new.

The Celtics secured their standing as the No. 1 defense in the league during the regular season, then supercharged their defense in the playoffs, culminating with an incredible showing against the Cavs on Sunday. And the scariest part? Head coach Brad Stevens still thinks his team has “a lot of room to improve” from Game 1.

That would be a tall order to fill. Boston held Cleveland to just 36 percent shooting as a team, including an awful 15 percent shooting night from the three-point line. That’s pretty troubling for a Cavs team that averaged the third-most three-point makes during the regular season.

Regardless, Boston emerged victorious — and it really wasn’t even close — 108-93 in Game 1, and their defensive intensity is primarily responsible for jumping ahead early and keeping the Cavs from make a serious run back at any point in the game.

Marcus Morris, for example, took the challenge of attempting to defend LeBron James — also known as the best basketball player on the planet. Morris called himself the second-best James stopper behind Kawhi Leonard. He held James to five points on 2-of-6 shooting in the 24 plays he defended him.

Morris, though, was quick to admit it wasn’t an individual effort that kept James at bay. It was a collective defensive push, including helping off of struggling shooters, that held James to a 15-point night on a poor 5-of-16 shooting night. Boston threw defender after defender at him, and even though Morris was tasked with the brunt of the defensive duties, it was a flurry of different looks that helped stifle James in Game 1.

That’s because when he beat one man, the help was always there:

Here comes the double again when he catches it on the block.

This is what happens when your team has versatile wings and a big man like Al Horford who can legitimately defend most positions. You get a defense that can switch on screens without missing a step or creating a real mismatch on the floor.

Throwing different looks at James is one thing. Protecting the paint is another. That’s where Horford comes into play. Horford isn’t your traditional uber-athletic or super lanky rim protector; He’s Boston’s rock, and he just might be the smartest center in the NBA, using his tools to anchor the paint every game.

Horford only had two blocks, but he deterred many, many more attempts at the rim. Stevens said Horford is important to everything the Celtics do. His impact on their defensive efficiency is at the top of the list of way he influences a game.

The Celtics held the Cavaliers to just 18 points in the first quarter and only a 35-point first half. Cleveland was battling from behind from two minutes after the opening tip. That’s because the Cavaliers — including James — just couldn’t find a way to get a basket against this stingy Boston defense.

Cleveland missed a ton of open shots, though, and James most certainly won’t shoot 5-of-16 from the field of 0-of-5 from three again this series. But Boston set the tone with the way they played defense in Game 1.

It’s the way they’ve played defense all year long. And let Brad Stevens tell it, the Celtics still have a lot more room to improve.