Diversify your bigs: how Rob Williams and Al Horford dictate the Celtics offense

Mar 30, 2023 - 4:00 PM

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In the playoffs, diversity and versatility are kings. Or king and queen? Co-emperors maybe? Either way, you get the point. Diversity and versatility, while related, are two different concepts. Versatility is about having players that possess skillsets that do a wide variety of things. Diversity, on the other hand, is about having players that do different things and solve different problems. Ideally your team is built around players that are versatile, which allows them to play with a diverse group of teammates. That’s part of the power of the Jays; their versatility unlocks the ability to diversify the lineups around them.

The Celtics can vary their approach based on personnel. This is especially true when it comes to offense, and the bellwethers of how the Celtics vary their attack are Robert Williams and Al Horford. Both are similarly versatile on defense, but much less so on offense (Al used to be extremely versatile on offense, but age has sapped him of his effectiveness as a rim roller). But that’s just fine, because the Celtics play into Al and Rob’s strengths, not in spite of them. If you look at the stats, you’ll notice an interesting trend.

When Al and Rob are on the court, either together or individually, the Celtics’ offense hovers somewhere between great and the best ever. So let’s take a look at how.

Rob on without Al

The Celtics leverage Rob’s absurd athleticism in several ways — some unique, some standard. One of my favorites is how they let Rob read his defender and cut in behind at any moment. It keeps the defense honest and/or leads to easy points.

Rob does such a nice job reading Joel Embiid in this second video, and it’s a common action that the Cs run with both Rob and Al off-ball. Rob knows Jayson Tatum is getting the ball off the pin-down, and that Embiid will stay high to help. He just slips between the Sixers defense and it’s an easy two.

His timing and his movement off drives play into his athleticism, and he’s constantly slipping into open space once his defender commits to help. He’s in the 87th percentile finishing cut possessions.

The threat of Rob just appearing next to the rim and dunking reaps benefits even when he doesn’t get the ball. For instance, Rob will often lurk in the dunker spot. When there’s a drive, the help usually comes from the defender guarding the player sitting in the dunker spot. Not when that player is Robert Williams.

Say “easy” more in that tweet Wayne Spooney. You can’t.

My inability to use a thesaurus aside, Norm Powell had plenty of time to get off Rob’s body and either take a charge or contest with verticality. He does neither. This is all made possible because Rob is really good at a simple thing lots of bigs struggle with, catching the damn ball. Rob has elite hands, and it allows him to bail out teammates regularly.

The real bread and butter with Rob though, is how dangerous he is in the pick and roll, and that serves as the foundation for the Celtics offense when he’s out there. Whether it’s Tatum, Jaylen Brown, Marcus Smart, Derrick White, or Malcolm Brogdon, most of the initial action when Rob’s on the court is a traditional high pick and roll, and we go from there.

He’s improved as a screener and does a nice job slipping when appropriate.

And often he will find himself setting the initial screen, and then when he doesn’t get the pass in the initial action, he slips into space like those plays above.

Part of what makes Rob so effective despite his relatively limited offensive repertoire is how well he reads the game. You see it when he’s in the dunker spot getting into soft spots, his timing on rolls, and with his passing chops. How many times have we seen him do something like this?

The talent it takes to battle on the boards and then immediately find an open shooter is something not a lot of players in the NBA have, never mind bigs. When you combine elite athleticism with a guy that can read the game at a high level, you end up with a weapon on the offensive end.

Al on without Rob

One of the more delightful things about the Celtics’ two-headed monster at center is how different they are. Rob basically doesn’t do anything other than dunk or layup (shoot more middies Rob, I’m begging you). Al, on the other hand, basically only shoots threes these days. 70% of Al’s points have come from 3-point range this season. That’s a similar range to noted big men Pat Connaughton, Gary Harris, and Luke Kennard. That doesn’t mean Al still can’t put it on the deck and punish defenses, in fact, that’s what makes his shooting so powerful. You can’t run him off the line, because if you do, he will pump and go and either get to the rim or make the right read and find an open man.

The biggest change in Al’s game as he’s aged though isn’t just how many 3s he’s taking, it’s the type of them. He’s become a shooter’s shooter, not just a guy that stands still and takes wide open ones. Case in point:

Both similar actions with the guard setting a screen for him, and then him floating to the 3-point line for a quick catch and fire. He’s sped up his release, and contests don’t really bother him anymore either.

Nevertheless, the bread and butter of Al’s old man game is standstill shooting, and he gets those shots in two ways. The first is pretty simple. Al pretty regularly spots up either in a corner or on the wing like an elite standstill shooter would. His shooting without Rob on the floor allows the Celtics to play 5-out offense, which opens up the paint. The Celtic ballhandlers attack this space relentlessly.

Second, just like Rob, a lot of primary actions involving Al start with him setting a screen on or off-ball. Very much unlike Rob, Al rarely rolls to the rim, unless it’s on the short roll to punish a trap. Instead, he pops, and boy is he deadly as a pop man. The Celtics do a lot of interesting stuff with Al setting pin downs and drag screens for an off-ball cutter, which leads to him popping for an open shot.

Al isn’t just a great shooter for a center anymore, he’s a great shooter for an NBA player. He’s in the 95th percentile on spot up possessions. Not among big men, among the entire NBA. It should be no surprise that the Celtics offense really kicks into overdrive when Al’s out there, with or without Rob.

Both Rob and Al on

Speaking of Al playing with Rob, this is when the real magic happens. The Celtics’ 121.6 offensive rating when they share the floor would shatter the record for most efficient offense of all time (currently held by this year’s Kings at 118.9). They are the perfect intersection of having a diverse set of skills, but enough versatility that they overlap in one very important place: passing. Al’s shooting keeps the paint open for Rob to roll hard and duck in when appropriate, and Al loves finding Rob in those spots.

This is everything on display. Double pin-down with Al and Rob, Al fades to the three-point line while Rob rolls to the rim and settles in the dunker spot. Al pump fakes, drives the closeout, and finds Rob for the lob. I would say “chef’s kiss,” but that’s not nearly enthusiastic enough for how much I love this play. Is there something more emphatic than chef’s kiss? Baker’s make-out session? We can workshop it.

But I digress and apologize. The diverse nature of Al’s and Rob’s skillsets allow them to cover up each other’s weaknesses, and their versatility allow them to complement each other’s strengths. The Celtics are able to play two centers and thrive on offense, which means they stay big and elite on the defensive end. And that’s a damn fine recipe for winning in the playoffs. Cook’s smooch.