Celtics vs. Cavaliers: 3 keys to the Eastern Conference Finals

Boston is 2-3 in in playoff matchups against LeBron James.

Al Horford knocks a rebound away from Cleveland's Tristan Thompson at TD Garden.
Al Horford knocks a rebound away from Cleveland's Tristan Thompson at TD Garden. –Photo by Matthew J. Lee/Globe staff


Fresh off a nine-day layoff, the Cleveland Cavaliers will return to the floor to face off with the Boston Celtics in the Eastern Conference Finals at TD Garden Wednesday night. The showdown looks like a mismatch on paper, particularly when you compare Cleveland’s eight-game postseason winning streak to Boston’s hard-fought series wins against Washington and Chicago. Outside of a late March blowout by Cleveland, these two teams had three tightly contested matchups in the regular season, which may be more indicative of a competitive series that could await.

What should Celtics fans be watching for as the defending champions come to town? Here’s a look at three things that will loom large in the sixth postseason series between the Celtics and LeBron.


1. The battle at the 3-point line

There has been no team hotter from the 3-point line this postseason than the Cleveland Cavaliers. The defending champions have knocked down 43 percent of their attempts from deep in eight straight postseason wins thanks to a well balanced attack. Nine players on the Cavs’ roster are shooting 40 percent or better from 3-point range during that span, and that doesn’t include one of the team’s best regular season shooters (Kyrie Irving). Comparatively, the Celtics had just three players above that mark. The type of floor spacing created by such shooting can be a lethal weapon when you have a player like LeBron James setting the table for your offense. The Cavs are due for some regression to the mean (38.4 percent in regular season), but they were still the second-most accurate team from beyond the arc all year long (Boston was 14th). The Celtics will be forced to pick their poison this series from a defensive standpoint, whether it’s adequately protecting the paint or limiting open 3-point looks for Cleveland. Boston will need incredible discipline defensively, as well as some luck, to survive the barrage

The best counter the Celtics might have to the Cavs’ attack may be trying to keep pace themselves from the perimeter. Boston is attempting more 3-pointers (34.9 per game) than any other team this postseason, and they have knocked them down at an above-average clip (37.9 percent). They’ll need to maintain that level of accuracy to have a chance in this series, but it is conceivable that they could outshoot the Cavs from deep with a few breaks, something they failed to do during three of their four regular-season meetings.


2. Keep Tristan Thompson from dominating the offensive glass

The Celtics saw in 2015 how much damage Thompson can do on the offensive glass, as they watched the 6-foot-9 power forward grab an average of nearly four offensive rebounds per game during Cleveland’s four-game sweep of Boston in the first round. Two years later, the 28-year-old has only gotten better, while the Celtics’ defensive rebounding has continued to regress. This postseason, Boston has allowed Robin Lopez and Marcin Gortat to be two of the best three offensive rebounders on the court. The third thus far has been Thompson, who has grabbed a staggering 18.8 percent of Cleveland’s misses while on the court.

Thompson’s length and athleticism are a challenge for any frontcourt, and he’s gotten the better of Al Horford on the block for two straight years in head-to-head matchups. In order to slow Thompson down, Celtics perimeter players will need to gang rebound relentlessly as Horford and Boston’s other bigs attempt to box him out. That mission is easier said than done, particularly when trying to contest Cleveland’s superb 3-point shooting as well. Kevin Love could also prove to be a problem on the glass, although he hasn’t emerged as a threat during this year’s postseason so far

It’s a daunting challenge for any NBA team to slow down the Cavs’ offense when they get just a single shot each time down the floor. If the Celtics also hand them extra opportunities on the glass, Boston is setting itself up to fail.


3. Cleveland’s subpar defense

An overwhelmed and shorthanded Raptors squad didn’t pose many problems for the Cavs in the Eastern Conference Semifinals, but an uptempo Pacers offensive attack did present some issues for Cleveland in the first round. Indiana scored 114.7 points per 100 possessions, the third-highest offensive rating of any team in the postseason, an impressive mark for a squad that was a mediocre offense during the regular season.

That type of production indicates the Cavs’ defense, despite an undefeated postseason, still has holes that resulted in 21st ranked defense in the regular season. An older, more offensive-minded second unit (Deron Williams, Kyle Korver, Channing Fyre) could give the Celtics an opportunity to prey on some of Cleveland’s weaknesses. One of Boston’s own biggest weaknesses this postseason has been turnovers, but the Cavs have been one of the worst teams in the league at forcing miscues all year long, including the postseason.
The Celtics have the firepower around Isaiah Thomas to stretch Cleveland’s defense out, particularly if Al Horford continues his sensational shooting all over the floor.