LeBron James had just finished his worst game of the postseason in a 108-83 loss to the Celtics, but he sat at the podium after Sunday’s Eastern Conference finals opener and said that Game 1s are “feel-out games” for him and that he “got a good sense” of how Boston played. After scoring only 15 points on 5-for-16 shooting with seven turnovers, what LeBron sensed was a defensive coverage that Brad Stevens and the Celtics hadn’t previously used against the Cavaliers.

The Celtics switched screens all game, even when it meant 6-foot-2, 190-pound point guard Terry Rozier would get stuck battling LeBron or Kevin Love. But Boston didn’t leave Scary Terry hanging; it aborted the obvious mismatch by switching assignments during the entry pass to the post.

Watch for the switcheroo as the ball is in midair—Jayson Tatum swaps places with Rozier. Love might toss around Rozier before the ball is delivered, but it’s meaningless when the man who ends up defending him is much taller, longer, and stronger.

The Celtics did this time and time again, whether it was Tatum, Jaylen Brown, or Marcus Morris taking over before the ball could be delivered. Switching is pervasive in the NBA because teams are using more versatile lineups, but it can sometimes lure the offense away from what it does best in favor of a perceived mismatch. It seems Stevens was betting on the Cavs taking the bait, and they did. The defensive tactic stagnated Cleveland’s offense into seeking mismatches that were only an illusion.

The NBA Playoffs Check out The Ringer’s coverage of the 2018 NBA playoffs

Cleveland wasted a lot of time screening, rescreening, and delivering the ball. It went away from running a regular offense. The big problem, however, was tempo. The Cavaliers have played at a snail’s pace all postseason, averaging 93.4 possessions per game, which would’ve ranked slowest by a wide margin during the regular season. Playing slowly isn’t inherently a problem, but the Cavaliers could spark offense by speeding up instead of letting the Celtics settle into their league-best half-court defense.

When LeBron brought the ball up, Boston employed the same defensive tactic it used in the first round against Giannis Antetokounmpo and last round against Ben Simmons: It had the big man—either Al Horford or Aron Baynes—shade toward the middle of the floor to contain James. Much like the Bucks and Sixers, the Cavs didn’t really test it. But when the big man is helping off of Love, it can lead to open shots.

If the Cavaliers push the pace harder, they can find more open looks like this one. Even if they don’t, they’ll be able to initiate their half-court sets earlier in the clock, which is vital. If they want to take advantage of Rozier switches, they’ll need to play faster by getting the ball up the floor quicker, rather than walking it up, and moving more quickly into their actions.

Had Love received the ball with 10 seconds on the clock rather than 0.7, the paint is wide open for him to drive. He could’ve ended up with a layup, drawn a foul, or found an open teammate. Instead, it’s a shot-clock violation. “I don’t think we played with enough pace to get to a good second, third [option],” Kyle Korver told reporters after the game. “That’s on us.”

This is more like what Korver and the Cavs should be looking for:

The ball was delivered as soon as James made contact with Rozier, so Boston had no time to play musical chairs. And LeBron got the ball with 15 seconds on the clock, rather than 4.5. Rozier on James is a death wish, so the Celtics doubled with Horford, leading to an open 3-pointer for J.R. Smith. Shots rarely fell for the Cavs, as they finished 4-for-26 from 3, but they likely won’t shoot that poorly again in this series. They need to keep finding their open shooters, but they need to do it more quickly.

It worked here. Love’s post-up is far enough away from the other side of the court that the Celtics aren’t in position to switch during the entry, and he secures the ball with 13 seconds on the shot clock. Boston expectedly doubles, and it leads to an open 3 by George Hill. But the Celtics, for the most part, did a good job of executing their midplay swap, and they threw at James some perfectly timed, swarming double-teams.

Brown wasn’t often tasked with defending James in Game 1; he was instead helping or stunting off the ball and sticking to Korver. Moving forward, the Cavaliers could target Brown rather than Rozier since the Celtics are going to swap out Rozier switches, anyway. Unlike with Rozier, Boston likely isn’t switching Brown off of James or Love during the entry pass, which could end up being a favorable matchup for the Cavs. He’s the most undersized option of their versatile forward trio, and he’s also dealing with a hamstring strain that kept him out of Game 1 against the Sixers. And on-ball slip screens featuring Korver would be a wrinkle for Boston to adjust to. “[We] expect to get a punch in Game 2,” Brown told reporters after the game. “We’ve got to weather the storm.”

Cleveland’s counterpunch will need to be more of a combination than a jab, and the Cavs’ postgame comments suggested they’re already formulating a plan. “When we post myself or Bron against a mismatch, we can’t just look at that first option,” Love told reporters after the game. “We have to be able to move and find cutters, and set picks away from the ball. We got away from that a little bit.” Love and Korver found a rhythm against the Raptors by running an off-ball screen action that led to countless open shots for the pairing, so it’s no surprise they’re the two players calling for movement. But the reality is the Cavaliers as a whole showed more movement in their last series against the Raptors.

Watch how Korver and Smith alternate setting screens for each other, which discombobulates the Raptors’ defense and leads to an open layup.

Or here, Korver cuts, then LeBron follows, leading to another open layup.

The Raptors had an average defense from mid-March on and struggled all season against elite offenses. Boston has the best defense in the NBA with a rotation full of smart, disciplined defenders, so it won’t open the floodgates like the Raptors did. But even great defenses aren’t exempt from getting picked apart. James and Love are two of the best passers at their positions in the NBA. More movement takes advantage of their roster full of excellent spot-up shooters—including one of the greatest ever in Korver—and Horford’s kryptonite in Tristan Thompson.

James and Love could also be used in more face-up or isolation situations from the elbow or wing rather than posting up down low. Love is at his best from the elbow, and having him out there opens up more cutting lanes for inventive off-ball cuts to work. In the second quarter, LeBron threw a lob dunk to Love, and in the third quarter, Love returned the favor.

“It’s not March Madness. You get better throughout the series. … I’ve been down 0-1, down 0-2, I’ve been down before,” LeBron said after the game. “There’s no level of concern no matter how bad I played.” James spent the large portion of the game deferring to his teammates, which he’s done in the past to “feel out” the opponent. In Game 2, he’ll likely turn on Terminator mode. But LeBron can’t do it alone. Trouncing Boston’s defense, or beating any potential NBA Finals opponent, requires more innovation.