It was a coup for the Boston Celtics on Saturday, landing an agreement with free-agent Al Horford as Danny Ainge began cashing in the truckload of assets left over from the Big Three era in Boston.

Ainge isn't finished, clearly. But it's worth pausing and recognizing the enormity of the deal from a Celtics perspective.

The common belief that the Celtics can't get stars to go to Boston actually was a major misnomer; Kevin Garnett and Ray Allen, in their own ways, had to sign off on going there in the trades that set the stage for Boston's most recent championship in 2008, banner No. 17. (Horford, in his glee over the agreement, tweeted 18 shamrock emojis -- surely not a coincidence.)

Still, the perception was there, and to be fair, neither Allen nor Garnett was a free agent, and certainly not in this kind of market where an All-Star player can pretty much pick his team and price. Horford had his pick. Oklahoma City would've loved to have him. Same with the Wizards. Hawks. Probably the Warriors if they don't get Durant. But Horford chose Boston, and he just so happens to have been one of the most Celtic-like free agents on the market.

Horford, 30, is at once outstanding and workmanlike at what he does. The shelf life being longer for big men, he's as worthy of his four-year, $113 million agreement as any of the beneficiaries of the NBA's free-spending largesse on the first two days of free agency. But if Horford couldn't get past LeBron James with the Hawks, the reality is that he isn't doing it with this Celtics team that he just signed with either.

Unless they get Kevin Durant, too.

Which leads us to the next questions in this free-agent frenzy: What else does Ainge have up his sleeve? And how does Horford signing with the Celtics affect Durant?

The Celtics courted Durant hard on Saturday, unleashing New England icon Tom Brady as part of their recruiting team. (Anything less would've been, you know, deflating.) Anyway, it's interesting that Horford chose the Celtics on many levels, but specifically on this one: His uncertainty about what Durant is doing led him to a place Durant is considering.

On one hand, the knee-jerk reaction is to assume that Horford choosing Boston means that Durant is indeed leaving the Thunder, who had been pursuing avenues to clear cap room to sign Horford and team him with Durant and Russell Westbrook. In fact, one of the factors that led Horford to leave the Hawks for the Celtics as opposed to the Thunder was, frankly -- like the rest of us -- he didn't know what Durant was going to do.

But here he is, still not knowing what Durant will do.

Could Horford have waited until Durant completed his remaining meetings with the Heat and Thunder on Sunday before making his decision? Of course he could have; with $1.72 billion handed out on the first day of free agency and more madness on Saturday, it's clearly a seller's market. But there were other factors. And Horford clearly was in no mood to let all of the connected parts play out.

Factor No. 1, according to league sources: Horford was none too pleased with how reluctant the Hawks were to come forward with a full five-year max. Factor No. 2: Atlanta's signing of Dwight Howard. Could there be a more contradicting force in the NBA to Horford than Howard, in terms of substance vs. style?

"He didn't want to play with Dwight," a person familiar with the situation told CBS Sports.

Does Horford choosing the Celtics over the Thunder imperil OKC's chances with Durant? The truth is, nobody except Durant knows. But there's another truth that should be considered before jumping to conclusions: If Horford's goal was to play with Durant, he could've accomplished that in Oklahoma City, with a team that has been to four of the last six Western Conference finals. If that's what it would've taken, the Thunder had several cost-cutting avenues -- including moving Enes Kanter -- that would've paved the way.

So really, nothing has changed on the Durant front. With a sitdown with Pat Riley scheduled for Sunday in the Hamptons, and then a final powwow with the Thunder contingent in the same Long Island locale, Durant wasn't ready to make a decision on his future on Saturday. Horford was. Simple as that.

For what it's worth, a person with connections to Horford told CBS Sports on Saturday night that rival executives assembled in Orlando for Summer League still believe that the most likely scenario for Durant is staying in Oklahoma City. In the end, Durant is the only one who can make that decision.

And he'll do it on his own time, not anyone else's.

Al Horford isn't waiting on Kevin Durant. USATSI