First, people seemed to think that Al Horford was going to pick up his player option for next season and return to the Celtics for one year and $30 million before hitting free agency next summer.

Then, in a relatively unsurprising move, Horford decided to decline his option and pursue a multi-year deal with the Celtics instead. It’s not uncommon for veterans like Horford to attempt this. At 33 years old, this might be his last chance to pursue long-term security. Locking in a 3 or 4-year deal this summer might be worth a little bit of a pay cut this coming season.

That said, there’s a little bit of risk involved for the incumbent team in these situations. While a deal is normally worked out, once a player declines his option, he’ll normally at least pick up the phone if another team calls.

That’s why it was major, if not totally shocking, when it came out today that Horford and the Celtics were no longer working on a three-year contract, and that he would instead be pursuing a four year deal with a different team in free agency.

For such a sudden change of heart, and for Horford to apparently call off negotiations with the Celtics, something dramatic needs to have happened—likely either a disrespectful low-ball offer from Boston, or a back-channel promise of a lucrative deal from a different team.

The latter was seemingly confirmed in a late-night tweet from Marc Stein:

So, some team found a way to express to Horford that they were ready to offer him a four year deal worth more than $100,000,000 on June 30th. That signal could have motivated him to decline his player option, and almost certainly motivated him to ask the Celtics for a similar contract in order to stay in Boston. But that’s a big price tag for a 33-year-old player—and one that a non-contending team like the Celtics, who are also resigned to losing Kyrie Irving this summer, would be irresponsible to commit to.

We can make a few guesses as to Horford’s destination. First, it’s probably a good team. Not only would he likely be uninterested in playing the last few years of his career on a lottery team, but lottery teams would likely be uninterested in paying over $100 million to an aging big man. Someone who is investing this kind of cap in Horford thinks that he is helping them win now, making the salary on the back end of the deal worth it. It’s also probably a team that has relatively easy access to the cash—if they’re promising this kind of deal ahead of time, I’m not buying that it’s a team like the Houston Rockets, who would have a ton of work to do to clear cap space. And while a sign-and-trade with the Celtics could become possible, it’s clear at this point that Horford’s mystery team is able to sign him outright. Boston definitely hasn’t been looped in this early to helping facilitate a sign-and-trade that will bring about the departure of one of their best players.

So, who are the good teams that could be in this conversation? Brooklyn, Philadelphia, the Clippers, Indiana, and potentially Utah are the teams that could make a 4/100 deal for Horford work. Utah isn’t quite at the necessary cap room level, but they’re just one small salary dump (likely Korver or Crowder) away from it, and their only big free agent is Ricky Rubio, who they are willing to renounce in order to add a big piece.

Philadelphia is probably the least likely of these teams to be in on Horford. While the Sixers technically have the potential cap room to make a play for any free agent, they have Jimmy Butler, Tobias Harris, and J.J. Redick all entering free agency this summer. Even keeping one of Butler or Harris likely takes them out of the running for Horford.

Indiana and Brooklyn are two up-and-coming Eastern Conference playoff teams, and it’s believable that both would target Horford. But at four years and $100 million, it feels a little steep for two teams that he doesn’t vault into contender status.

It seems most likely to me, though I’m not certain, that the Clippers are Horford’s mystery team. The puzzle pieces seem to fit together a little too well.

First, let’s assume, as reports seem to indicate, that the Clippers are in the lead to sign star free agent Kawhi Leonard. If they do, they immediately are vaulted into contender status—and with the championship window suddenly opened and the clock ticking, it would make sense to make another splash and add Horford, who likely would supplant Gallinari as the team’s second-best player.

Speaking of Gallinari, the math for Horford’s supposed 4-year, $100M contract works out curiously well with the Clippers’ cap situation. If the Clippers waive the non-guaranteed contracts of Sindarius Thornwell and Tyrone Wallace, and then renounce their cap holds for all of their free agents (except for the qualifying offers for restricted free agents Ivica Zubac and Rodney McGruder), they’re left with a team salary of $53.6M for eight players and four empty roster holds. With a projected salary cap of $109,000,000, that leaves them with $55.4M in room. First, they’d sign Kawhi Leonard to a maximum-salary deal worth $32.7M.

That leaves them with $23,614,829 in remaining cap space to sign Horford. With the max-allowed 5% annual raises, that contract ends up being $101,543,768 over four years. The salary slot that the Clippers will have for a secondary free agent just happens to be almost exactly the same amount as Stein reported for Horford.

Beyond making sense for a Kawhi-led Clippers’ win-now timeline and L.A.’s cap availability, Horford would be a stellar on-court fit for the Clippers. He’s a very, very good and versatile player, making him a good fit in most situations, but it’s easy to get excited about what he would bring to the table in L.A. He’d likely start at center, but his defensive versatility and floor spacing make him a viable option to soak up minutes at power forward and play alongside Montrezl Harrell. In fact, given his age and the rumored four-year duration of the deal, any team that lands Horford would probably want to do their best to preserve him physically by limiting his minutes, playing him at power forward to reduce the strain of his minutes, and strategically resting him throughout the year.

The Clippers are well-equipped to do that. With backup center extraordinaire Montrezl Harrell under contract for next year, and Zubac likely to return for cheap, the Clippers have plenty of options to soak up playing time down low, keeping Horford hopefully well under 30 minutes per game. And when Horford sits games for rest, the Clippers can simply start Zubac, who is limited but proved perfectly serviceable as a starter last season.

There’s one other reason why I strongly suggest that the Clippers are Horford’s mystery team, though. I’m going to lay out some puzzle pieces here:

Kyrie Irving and Kevin Durant have been long rumored to want to team up in New York.

Kyrie recently signed with ROC Nation, Jay-Z’s agency, which also represents Durant.

Jay-Z used to be a part-owner of the Brooklyn Nets before selling his stake so he could get into the agent game—but he is still Brooklyn’s highest-profile fan.

Reports are indicating that Kyrie Irving is expected to join the Nets in free agency this summer.

Right as Kyrie to Brooklyn began really heating up, the noise began around Horford leaving Boston.

The Nets are rumored to be trying to off-load Joe Harris’ contract. Joe Harris is a really good player on a reasonable, expiring deal. He contributed a lot to Brooklyn’s playoff run last year. Looking at their cap sheet, they have enough money for a second 30% max salary next to Irving. But in order to have a 35% max salary, they’d need to clear Harris’ contract—and Kevin Durant is the only free agent candidate for such a deal this summer.

The Clippers’ top priority this summer, all along, has been to try and pair Kawhi Leonard with Kevin Durant in L.A.

Here’s what I think. I think that the Brooklyn Nets believe they are signing Kyrie Irving and Kevin Durant, based upon the longtime rumors, the ROC Nation-Jay-Z connection, and the Joe Harris rumors. Moves of this magnitude naturally have ripple effects around the league, including that Boston all of a sudden valued a win-now veteran like Al Horford much less than they did when they thought they were keeping Kyrie. And if Durant has indicated that he is joining the Nets, a team like the Clippers would look for a plan B to pivot to. The newly-available Horford would be a natural target.

We know that the Clippers aren’t keen on giving a four-year max to players like Jimmy Butler or Kemba Walker. It’s messy positionally and poor value at 4 years and $140M. Remember, this is the team that balked at giving Chris Paul the 5th year on his max deal, traded Blake Griffin’s max deal for more flexibility, and traded Tobias Harris in order to avoid potentially giving him a max deal in free agency. They clearly don’t like maxes for guys who aren’t in the very top tier of the league.

But the Clippers desperately want to give a max contract to Kawhi. In order to do that, they might need to also give him a better second-best player than Danilo Gallinari—or, even if he’s coming anyway, they might just like the idea of adding another major piece this summer. Short of giving the aforementioned max deal to Jimmy Butler, Horford is probably the best win-now piece in a sub-max tier that includes the likes of Tobias Harris and Harrison Barnes.

I don’t know whether the Clippers are Al Horford’s mystery team or not. And, to be totally frank, while I love Al Horford, I’m not sure that a 4-year, $100M deal for a 33-year-old is a wise investment. But it undeniably would boost their odds at winning a title within the next few years—and that’s just one of several angles from which the Clippers seem to make the most sense as Horford’s likely suitor.