Skill or luck? Analyzing the Celtics’ elite 3-point defense against the Heat

(Kevin Cox/Getty Images)

Defending the 3-point line has generally been a calling card of Brad Stevens’ best teams. Boston finished 2nd in the NBA in 3-point defense during the regular season and that success has continued this postseason as the C’s rank first by a wide margin (four percent) in 3-point defense by holding opponents to just 30 percent accuracy from beyond the arc.

The Eastern Conference Finals were supposed to be the true test for the C’s on this front, facing a Miami team that had shot the lights out over the first two rounds.

37.3 percent vs. Milwaukee, six players shooting over 35 percent
39.1 percent vs. Indiana, five players shooting over 35 percent

That success continued early in the East Finals against Boston as Miami knocked down 44 percent of their 3s in a comeback Game 1 win. However, even as the Heat still hold onto a 3-2 series lead heading into Game 6 on Sunday night, it’s hard not to notice an integral part of their offense coming crashing back down to earth.

Despite a hot Game 1, the Heat are shooting just 30 percent from 3-point range in this series. Over their last three games, that number has drifted down to 24 percent, cratering in Game 5 with a 7-of-36 performance (19.4 percent).

“They're very good at defending the three-point line,” Erik Spoelstra said Saturday of the Celtics. “They've taken us off of some of our normal rhythm threes. I think we've also missed some open ones. We just have to work more persistently to get the type of shots we want in our wheelhouse, which we're very capable of, even against a very good defense like Boston.

“Our guys are extremely ignitable. It can happen just like that. But we have to do a lot more things defensively where we're not just hoping that we make a bunch of threes and a bunch of shots.”

Upon further investigation of the struggles, there are drop-offs everywhere for Miami's high volume shooters but a couple of the slumps have to be considered alarming for a team so reliant on the perimeter to score.

3-point shooting against Boston

Robinson: 35.7 percent
Herro: 35 percent
Jones Jr: 33.3 percent (1-of-3)
Dragic: 32 percent (5-of-21 in last three games)
Crowder: 26.2 percent (3-of-23 in last three games)
Butler: 22 percent (0-of-5 in last three games)
Olynyk: 20 percent (1-of-6 in last three games)
Iguodala: 20 percent (1-of-8 in last three games)

So what exactly is causing the recent drop-off? Boston’s defense? Shooting luck? We all know Boston benefitted from a lot of shooting luck early in Game 4 when they came out flat so I turned to Friday’s Game 5 effort as a better gauge of where the Celtics defense is at. Just how much did the C’s defensive energy impact Miami’s outside shooting? I watched all 36 3-point shots to find out. Here’s a rundown of those attempts along with some takeaways.

First Half

--Duncan 3 make (good Theis contest)
--Crowder open corner 3 (Kemba helps at rim, leaves Crowder open)
--Dragic miss lightly contested 3 (Tatum)
--Duncan miss lightly contested deep 3 (Brown)
--Crowder miss 3 (good Theis contest)
--Iguodala miss open corner 3 (Tatum takes away Adebayo roll to leave open)
--Duncan 3 make (Tatum contested)
--Duncan 3 miss (good late switch and contest by Grant)
--Iguodala corner 3 (good Wanamaker late switch and contest)
--Olynyk miss (Brown late contest)
--Dragic open wing 3 (Wanamaker plays help defense in lane, leaves open)
--Herro miss open transition 3 (Walker late contest)
--Crowder stepback corner 3 on offensive rebound (good Kemba contest)
--Crowder miss wide open 3 (Jaylen blows 2-3 zone defense coverage that C’s had disguised)
--Robinson makes corner 3 (Jaylen loses him briefly)
--Robinson misses 3 (Smart contest, Jaylen leaves him to help Dragic)

2nd half

--Duncan misses 3 (Jaylen trails behind, off balance)
--Duncan pull up corner 3 (Jaylen light contest, tough shot)
--Duncan misses 3 (Smart contests after trying to switch onto Bam)
--Crowder miss corner 3 (late Kemba contest)
--Dragic miss handoff 3 (Kemba good contest after going under)
--Dragic make 3 (tough Smart contest)
--Butler miss 3 (late Smart contest)
--Robinson miss wing 3 (good Theis contest)
--Dragic miss pullup 3 (good Grant contest)
--Herro pullup transition 3 on Hayward (late contest)
--Dragic miss top of key 3 (great Smart D tough shot)
--Dragic miss corner 3 (Hayward miss switch, late Smart contest)
--Iguodala miss open wing 3 (Hayward contest)
--Herro miss open kickout 3 from corner
--Crowder miss stepback transition 3 (late Theis contest)
--Herro make 3 on Smart pin down
--Robinson miss 3 (Smart good contest)
--Herro miss 3 (good contests)

1. The Celtics did a far better job of eliminating wide-open shots in Game 5: The Celtics gave up a number of good looks but any team is going to do that over the course of 48 minutes. However, Miami’s best shooters always saw a hand in their face even if it was late on the release. The Celtics' tightly contested shots went up from an average of 9.6 during the series to 13 in Game 5. On the flip side, open shots declined in number (10 compared to 15.4 on average in the series). A big part of that came due to the C’s work on the defensive glass. Countless second chance opportunities for Miami in this series led to kickout 3-point attempts that were wide open. Miami was held to zero offensive rebounds in the second half so those easy looks just vanished.

2. Boston’s bigs did a much better job switching onto elite shooters: This is where some