Active and attentive: How Al Horford set the Celtics' tone in Game 1

In the matchup of the playoffs thus far, the Boston Celtics squeaked out a 115-114 victory over the Brooklyn Nets in Game 1 of their first-round series.

Jayson Tatum played a demonstrative game, putting up 31 points, 8 assists and 4 rebounds, including the game-winner as time expired. Kyrie Irving had a domineering 39-point performance that kept the Nets' engine revving in spite of a rough shooting night from Kevin Durant.

But in both watching the game in real time and going through the film, I'm not sure I could come away more impressed with a player than I did with Al Horford's play. All around, this may be the best game the 35-year-old has played since the last year of his first stint with Boston.

Horford has played fairly well all year, still stalwart as a starter in the league. A friend who's a scout jokingly texted me at halftime, "Horford with rest is an All-NBA player," and in Game 1, he looked the part! The activity and attentiveness he played with was absolutely tremendous.

Horford set the tone early with consistent activity and timeliness on switches off-rip.

Horford cheats in off of Bruce Brown (a common theme), and ultimately calls for the switch as Jaylen Brown was taken out of the picture by Andre Drummond's screen. Daniel Theis shades as well, and allows Big Al the half-step he needs to recover. Then, watch the aggressive switch onto Seth Curry. 

I cannot illustrate enough how awesome that play is from Irving (one of the best off-ball movers and spacers in the league), as he runs into a dribble-handoff with Curry after being walled off. Against the majority of teams and defenses, that's an open shot as the switched big gets lost or contemplates the open lane the defender might give up. Horford completely blows up the impromptu play.

The play ultimately results in a dump off for Drummond, preceded by an early overhelp from Theis that you can see the duo communicate about after the possession ends. Yet, the point remains, Horford was fantastic here. Defense is often times reduced down to stops, and I think we can lose some really incredible plays and process in that shedding. It is HARD to be elite on defense, but this is an exemplary play from a big that shouldn't be judged strictly on whether or not a bucket happened.

The tightness of the help and switch erases the space for a pull-up jumper. Riding out the drive with his hips and hands up-and-out takes away the attempt around the rim. The second switch removes any chance of an open shot off the outlet. Again, it's not a stop, but that's three fantastic plays forcing an elongated possession, symbolic of Horford's night as a whole on that end.

Durant and Irving of course made shots as they are apt to do, but man, just look at how difficult it still is.

Horford's help was masterful, as he imposed himself all over the court. He toed the line between completely cheating off his assignment to stalk the lane, while also being aware of his man and recovering when necessary. His ability to take up space in potential driving lanes without getting beat backdoor or with a skip pass was also huge for containing the Nets to a more difficult shot profile. Boston's defense as whole ebbed and flowed throughout the game, which is understandable given the level of offense the Nets bring to the table.

Horford was a constant positive throughout.

As the Nets shifted to lineups with Nic Claxton at the 5, Horford made his presence felt on the glass (finished with 14 total rebounds) and in the paint. Switching with Claxton was more viable defensively than with Drummond at the 5 for the Nets, but shifting Horford more to the interior rather than fully slot in the corner allowed Boston to counter, using its size in the paint. The difference in size between the two teams as the game wore on was staggering, and it played out, as the Celtics outrebounded the Nets by 14 (with the game-high from Horford being the literal difference).

This first quick seal in early offense sucked in the defense, and then the flip to do his signature "Horford seal" on Irving opened the direct driving lane on the dunk by Brown.

As the Nets tried to deny the ball to Tatum and Brown, Horford's post-entry passing and DHOs were key to opening up ball-handlers down the stretch and lubricating the offense. 

How Horford is respected (or not) as a jump shooter will be an intriguing storyline webbed within the X's and O's of the series. He struggled from deep on the season, but went 2 of 2 in Game 1, including a doozy of a make off a screen.

It felt pretty clear in-game that the Nets were willing to live with any open Horford shots, as they comfortably sagged off of him when he was off the ball the majority of the game. Boston's awareness of that fact, and willingness to shift because of it, was all the more impressive.

While it would be unreasonable to expect Al Horford to play to the lofty heights he did for the remainder of the series, his brilliant play was a significant reason for a Celtics victory in the opener, and lends credence to a potentially dynamic postseason run.

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