In honor of Kevin Garnett’s 36th birthday, I just head-butted a basket stanchion and unleashed a 45-second monologue of nothing but four-letter words, and I will heretofore act half my age while pretending that last night’s thorough collapse never happened (at least once this post is published, or until referencing the collapse again makes sense, probably while slamming my head repeatedly against my desk). For my gift to Garnett, I will never again call him old. Even though he is.

Garnett will wake up this morning, slap himself in the head a few times, listen to the happy birthday voicemail he received promptly at midnight from Charlie Villanueva, wipe away nightmares of Thad Young running wild through the Philadelphia night, eat a crowbar for breakfast, drink a double dosage of the Elixir of Life from his hip flask, look in the mirror and remind himself, “You’s an ill dude.” To celebrate the occasion, he’ll probably take an ice bath and head over to the gym to shoot 500 midrange jump shots.

The Celtics gave one away last night. You know this, I know this, Garnett knows this, the lunch lady in the cafeteria serving sloppy joes knows this. At halftime last night the Sixers were doing their best to simulate what would happen if a team started five Ben Wallaces. The crowd released a string of boos to reward such a miserable effort, but Boston led by just 15 points at halftime when the advantage should have been 30.

The Sixers seized the game with a late run, but the Celtics really should have stomped them out in the first half when they had the opportunity. One reason for the Celtics’ inability to put Philly away in the opening 24 minutes even when the Sixers had “please, end our misery” tattooed across their foreheads was an old issue: Boston cannot score efficiently with any consistency. After erupting for 12 points in the first 2:33, the Celtics scored just 12 more over the next 13 minutes. Another reason included “THREE OF THE FOUR RESERVES IN WHOM DOC RIVERS RELIES ARE RYAN HOLLINS, KEYON DOOLING AND THE INCREDIBLY STREAKY MICKAEL PIETRUS.”

What went wrong in the ensuing half? As Doc Rivers said, according to ESPN Boston, “Everything we did was the prescription that you don’t do to beat them. [A] 17-5 [edge] on offensive rebounds, 17 turnovers, 36 free throws — you would have thought we were down the whole game if you looked at those numbers.” Rivers also explained, “”We did more than settle; we lost our composure. We stopped running our stuff. Whenever that happens, I always think that’s me. I think that there is something the coach can do to slow them down, to get them back in their sets, to get them back in their rhythm, and I couldn’t do it. To me, I always think that’s my fault.”

An old, wise team played the part of discombobulated young whippersnappers for the second time in four games. The famed Celtics defense broke down to allow several wide open dunks. Dribble penetration came easily for Philadelphia, and help never arrived. The below-average Celtics offense was just that. Rebounds were ignored, cutters ran freely without any opposition, and my memory keeps reminding me that Ray Allen had very little chance of staying in front of anybody he defended.

And yes, Garnett was not good. He still rebounded better than any of his teammates and defended like the pick-and-roll-stifling prototype he is, but Garnett fell back to Earth yesterday — and he landed with a thud, with Lavoy Allen and Doug Collins standing over him baring their teeth. Despite getting a number of makeable shots, Garnett finished 3 of 12 from the field for just nine points. He committed seven turnovers, many of which resembled the time Tony from “Blue Chips” threw a game while playing for Western University and coach Pete Bell.

The Celtics are not going to win games because of their depth. Allen is struggling with his movement and struggling to hit shots (after last night’s 1 for 4, he’s now just 9 for 31 from the arc for the postseason). Hollins is shooting 7 for 21 (33.3%) in 114 playoff minutes, with just 18 points and 15 rebounds. He sometimes makes great defensive plays, but he also might launch a turnaround fadeaway airball from 14 feet. Pietrus could hit his next five shots or miss his next 45. Keyon Dooling hasn’t provided much besides pressure defense and a bunch of great locker room quotes.

With so much going wrong with the second unit, the Celtics have been overly reliant on Garnett to win games. His absurd plus-minus stats in the playoffs (the Celtics were 56 points per 100 possessions better with Garnett on the court entering yesterday’s game) paint the picture. Yesterday, Garnett was not the wrecking ball he had been. It wasn’t the only reason for the loss, but it was one of the important ones.

Happy birthday, Big Ticket. Here’s to hoping your first performance as a 36-year old bests your final at age 35.