A photoshop of Al Horford in 76ers blue last year would’ve sent the Ben Simmons-mocking wing of Celtics fans into fits of laughter. Now Joel Embiid is the one laughing.

Horford’s value to the Celtics may only become fully realized in his absence. He held Embiid to 19-for-52 (36.5%) shooting last season in individual matchups. Next season he will enter games in Boston from the visitor’s locker room. Horford is signed for four seasons in Philly, with a game and new team built to last.

“Horford’s taking a pay cut,” capsized into, “he’s leaving” within one week; only to shift into a last-minute scramble by the team to keep him that faltered. That false hope rendered the announcement that he would bolt to Philly a spear through Boston’s head. After the tease of a return alongside Kemba Walker, it had to be Philadelphia.

Losing Horford will stall the Boston’s growth. Al choosing Philadelphia hurts the Celtics’ competitiveness. Their scramble to maintain Horford on the eve of free agency highlighted what we learned again last year.

Danny Ainge stood in no position to replicate or even offset Horford’s loss. When he left the floor in the playoffs, the Celtics were outscored by 16.3 points per 100 possessions. Irving — by comparison — was a -3.7 in the playoffs (BRef).

An injury in-season, or the slight chance of Horford walking later, would leave the Celtics’ in shambles, whether they were competing or rebuilding. As they toed that line — the silver lining of the Walker signing turned grey.

The possibility of Horford departing only received due attention in Milwaukee following Game 5. Even then, it hid in the shadow of Kyrie Irving’s precarious standing in Boston. Horford pointed reporters to management, they would determine the future. Management tried, and apparently failed. The “we” Horford used then is devastatingly no more.

Something spurred him to disengage from Boston this summer. If it was exclusively money, then the pay-cut rumors were either wrong or changed. Boston’s situation did shift, due to Irving’s departure, which would lend credence to a shift. But the Celtics’ seized a Walker agreement before Horford agreed to sign with Philly — as far as we know.

If Boston simply would not match Philly’s money, they made a mistake. If Horford simply grew tired with the drama and disdain within last year, the Celtics are paying an extra price for their 2018-19 failure.

Maybe Boston never knew Horford would join the 76ers instead. Al improving a chief competitor — and raising their standing in the league — while directly combating Boston on the floor is problematic.

Four years could have worried the Celtics, though Horford previously stated his desire to play until he’s 40. Any youth movement in the paint needed Horford as a transitioning force. Daniel Theis has not played minutes against front lines. Robert Williams has only battled G-League front courts. Grant Williams’ resumé is the SEC. Tacko Fall — forget it.

Horford would have played a critical role in setting up Jaylen Brown and Jayson Tatum’s development too. He may be aging, but so is Walker — on the edge of his 30s entering a four-year pact.

I would never knock Boston for signing an All-NBA player that wanted to come. The Walker signing dispelled fear that players would turn their nose to Boston after a disastrous season. That cannot be the lone objective though. Committing $140-million to a player should carry an end goal — namely competing for the conference.

The cap never made it a Horford-or-Kemba choice. Boston’s post-Irving plans needed Horford as much if not more than Walker. Though timing is everything. Walker inked first, adding additional steps to retain Horford.

Boston scrambled to reclaim Horford’s bird rights on the afternoon preceding free agency, indicating they would negotiate. Philly certainly out-bit Boston. The cost of losing Horford plus the 76ers’ improvement becomes the tax of not paying.

The Celtics also stalled because the Nets did not have the incentive to acquire Irving through a sign-in-trade. Boston needed to make it worth Brooklyn’s troubles with a first-round pick. The Nets ultimately paid to hard-cap themselves in trading Kevin Durant. The strongest message of the Horford saga arrived from Steve Bulpett: Horford would not return no matter the Celtics’ efforts.

Source close to Horford says that even after all the Celtics' cap gymnastics, he will not be winding up back in Boston. — Steve Bulpett (@SteveBHoop) June 30, 2019

Bulpett followed Horford’s intentions across rapid shifts in negotiations. According to his reporting in mid-June, Horford desired extra years in exchange for a team-friendly annual figure. Somewhere communication broke down.

While the hyped arrival of Walker in Irving’s place, with good-guy draft draftees, allowed for a palatable summer; the loss of Horford is an inescapable hurdle the team will now attempt to surmount.

Horford aligned the team’s defense and facilitated volcanic offensive performances. His eruption each postseason propelled deep runs. Remember the Isaiah 53-point game? That Jayson Tatum dunk in Game 7? Those games never occur without Horford.

He could not save Boston from its demise in 2018-19. But like Marcus Smart, it’s scary to imagine how much further the situation could have slid without him.

Last year may have worn on him down like it did us. We weren’t even in the locker room. Perhaps there’s no way the Celtics could have retained him, and those comeback rumors were leverage for more money in Philadelphia.

While Irving will catch all the boos from fans at TD Garden, it will be Horford doing the most damage to the team they cheer for.