CLEVELAND – With their All-Star point guard out for the remainder of the postseason, the Boston Celtics had no choice but to make changes to their offense. Isaiah Thomas ranks fifth in usage rate and seventh in ball screens used per game in the playoffs. Through Game 2 of the Eastern Conference finals, Thomas was the ball-handler on 54 percent of the Celtics' postseason ball screens, according to SportVU.
In Game 3, we saw Marcus Smart use 24 ball screens, more than twice his average through the Celtics' first 15 playoff games. The biggest reason the Celtics won is that Smart shot uncharacteristically well. But though he played like Thomas in one sense, he still doesn't have the quickness that Thomas has to get the defense moving on a pick-and-roll. So Thomas' absence also produced an increase in post-ups, mostly for Al Horford.
The Celtics posted up on 28 of their 92 possessions in Game 3 on Sunday. They started early, going to Horford in the post on their first two possessions and either Horford or Smart on nine of their first 14.
Sometimes, they had mismatches. That first possession was Horford against J.R. Smith after a switch. Sometimes, they didn't. That second possession was Horford against Tristan Thompson. They posted more with their starters, but Kelly Olynyk also got to the free throw line a couple of times after backing down Smith and Kyrie Irving following a switch.
The league doesn't post up as much as it used to. According to Synergy play-type tracking, only three teams posted up on at least 10 percent of their possessions this season. Just five years ago (2011-12), 13 teams did so.
The numbers tells us that post-ups are the most inefficient way to score. There were 37 players who took at least 100 shots on post-ups this season, and only five of them had an effective field-goal percentage better than the overall league average of 51.4 percent.
For the most part, though, the Celtics are looking to pass out of the post.
"We've tried to make a huge emphasis on playing through the post all year with Al as a passer or Smart as a passer," Celtics coach Brad Stevens said after practice on Monday. "We get some of our better traditional motion or cutting actions when the ball goes in the post. Sometimes the guy that gets it in the post scores, but a lot of times it's to get other actions."
Think Avery Bradley making a cut into the paint from the wing or along the baseline from the weak-side corner. Maybe there's an off-ball screen to free a shooter beyond the arc.
"It's just a good way to give our group a different look," Horford said. "We play a lot of pick-and-roll. We do a lot of motion stuff. So it's good to have a good balance and post."
With the ball in the post, it's more difficult for defenders to see both the ball and their man, while also staying between their man and the basket. Those fundamentals of defense are easier with the ball on the perimeter. With a screener coming at you and your head can get turned around for a split second, just enough for a cohesive offense to take advantage.
"People just tend to look at the post-up as the one-on-one isolation play," Stevens said. "I think a lot of teams are using it as a passing play because of the angle at which you can start to cut and do those types of things. Golden State is probably the best at it, where they throw it in there and slip all those screens and you're sucked on to those shooters and you don't want to help and they get all the dunks."
According to SportVU, the Celtics rank second (behind San Antonio) in total post-ups this postseason, while the Warriors rank third. And the two teams most likely to pass out of the post have been Golden State (about 47 percent of the time) and Boston (about 42 percent of the time).
One key fourth-quarter basket in Game 3 came on a Bradley baseline cut off a Smart post-up (with help from a Jonas Jerebko screen that flattened Deron Williams, Smart's original defender, for several seconds).
Later in the fourth, with Horford posting up, two Cavs reacted to a Bradley cut as Smith fell down), leaving Olynyk open in the paint.
The Celtics' biggest post-up possession, though, was designed out of a timeout for Horford to score. Bradley cleared out to the weak side, giving Horford space to operate against Tristan Thompson with less than a minute to go.
Horford hit a short runner over Thompson to give Boston a three-point lead.
"That play, specifically, was to go score," he said Monday. "Coach called on me to score the ball. I read it. I saw that there was no help. It was one-on-one, so I took advantage."
In Game 3, the Celtics scored 1.32 points per possession on the 28 possessions in which they posted up and 1.16 points per possession on the 64 possessions on which they didn't. Shooting out of the post may be inefficient, but playing out of the post doesn't have to be.
Without Thomas, the Celtics had to adjust on the fly, down 2-0, playing on the road against the defending champs. But they didn't have to start doing things they've never done before. The stuff they incorporated to a smaller degree during the course of the season just became more prominent on a bigger stage. And it will surely be a big part of the Boston offense in Game 4 on Tuesday (8:30 p.m. ET, TNT).
"With Al's ability to pass, with Smart's ability to pass," Stevens said, "those are things we've tried to incorporate more of this year. And with this group, without IT, it's one of the things we'll try to do."
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