It's something that could end up being a constant as the series unfolds, and the winner of the chess match -- with Horford acting as the ever-movable queen -- may be the team that leverages it the most.
The Celtics stayed out of that matchup in Game 1. James attempted only two shots against Horford, making one. The Cavs' need to use Thompson instead of sharpshooter Kyle Korver at times made Stevens' game plan with Horford work well.
"He's our rock," Stevens said. "He's the guy we really, really lean on."
Al Horford provides a huge lift for the Celtics by hitting his first seven shots in Game 1 vs. the Cavs.
Horford played against them with the Atlanta Hawks in 2015 and '16 and didn't take part in a single win, getting ejected from one game in 2015 for a flagrant foul. Last season, he absorbed another lopsided series loss after moving to the Boston Celtics. In the final game of his season, Horford mustered just eight points and three rebounds, going out meekly.
The Cavs tried to go back at Boston, looking often for Love early in the game. Horford and Marcus Morris, who switched onto Love at various points, won that one. Love was just 5-of-14 shooting. Eventually, Cavs coach Ty Lue went away from his game plan and brought Thompson in to play center to take the burden off Love defensively.
Without Irving, the Celtics rely on Horford as a hub of their offense. Using him in the pick-and-roll, his ability to shoot from the outside, drive to the rim or suck in the defense and look for others makes him the closest thing you'll see to a point-center.
Horford has always had this set of skills, plus his ability to defend multiple positions. In the past, the Cavs have survived it by trying to pull him away from the basket. And James has throttled him at times over the years, attacking when Horford was defending him.
Horford was brilliant in the role on Sunday in Game 1, continuing his phenomenal play from earlier in the postseason to contribute 20 points, 4 rebounds, 6 assists and 2 blocks in Boston's 108-83 thrashing. And he was plus-17, thank you very much.
Tyronn Lue acknowledges that the Cavs didn't play well and says that Boston scoring 60 paint points "is way too many."
With Love known as a weak defender, Stevens repeatedly called Horford's number as the Celtics built an early lead Sunday. Horford tortured Love by stepping back for 3-pointers, driving right at him or setting the Cavs up by finding the open man when they brought Love to help.
This is the fourth consecutive year Horford has seen LeBron James, Kevin Love, Tristan Thompson and other Cavs up close in the spring. He may have spent more time with them on Mother's Day than his own mom over the past few years.
In an effort to put five shooters on the floor as much as possible, the Cavs have gone small this postseason and made Love the starting center. That makes the Horford-Love matchup a crux point in this series and opens up an opportunity for Horford to strike back at the Cavs.
"I feel like the coaches came out with a great game plan for our group," Horford said. "We just bought in and did what we were supposed to do."
When including a 2009 series sweep loss to the Cavs, Horford came into the Eastern Conference finals with a 1-15 playoff record against James-led Cavs teams in the postseason. James and a collection of Cavs big men have been merciless against him, averaging just 10.9 points and 4.3 rebounds against the Cavs in those 16 games. His plus/minus in that matchup was a gruesome minus-236, per data tracking by ESPN Stats & Information.
BOSTON -- The Cleveland Cavaliers' dominance of the Eastern Conference over the past three-plus years can be epitomized by what they've inflicted on one of the conference's All-Stars: Al Horford.
Al Horford talks about his leadership role amid contributions from his younger teammates after Boston beat Cleveland 108-83 in Game 1. (1:09)
Celtics coach Brad Stevens seems to think so, as he saw that matchup as one he could exploit based on his game plan Sunday. The Celtics put Love in 13 pick-and-rolls when he was on the floor with starting point guard George Hill in Game 1, clearly something they wanted to exploit. In all, the Celtics ran 41 pick-and-rolls at Love and Thompson combined, according to Second Spectrum tracking, and Horford was involved in most of them.
In other words, Horford badly wants to pivot from this black hole in an otherwise wonderful career. He may be getting the best chance he's going to get right now.
"[Horford's] playing at a very high level," Love said. "He's really been an ace in the hole for them."
Kevin Love talks about how the Cavs never got into a rhythm in Game 1 and their mindset moving forward.
Stevens has praised Horford's play and leadership since Boston won the derby to sign him in 2016, especially this season, as the Celtics have endured injuries to stars Kyrie Irving and Gordon Hayward.