PHILADELPHIA — With the trade deadline wheeling and dealing, and the pre-existing injury-related gaps in the 76ers’ rotation, the back half of the season was always going to involve building the plane while in mid-air.

Even if the ultimate destination is, at this point, no more luxurious than the play-in round, the process might still be applicable beyond early April.

Among those quandaries is what the backup backcourt might look like, especially on nights like Tuesday where Kyle Lowry and Eric Gordon aren’t available. But even answers to those questions mean little if the big guys aren’t in anything close to their usual form.

On a night where Tyrese Maxey scored just five points and Joel Embiid committed a late turnover, even bursts off the bench from Jared Butler and Quentin Grimes weren’t enough in a 106-103 loss to Toronto.

With it comes the Sixers falling to a season-worst 13 games under .500 at 20-33. It keeps them behind Chicago, a Bulls team that was busy scoring 21 points in the first half Tuesday night against Detroit, for the 10th spot in the Eastern Conference.

Lowry missed out with his chronic hip issue that coach Nick Nurse said isn’t going away anytime soon. Gordon, after a sore knee last week, missed this game and almost certainly will miss Wednesday’s against the Nets with a wrist sprain. That left minutes for Butler, who scored 15 points on 6-for-10 shooting, and Grimes, who had 13 points and seven rebounds. But with Maxey shooting 1-for-9 for five points and every starter save for Joel Embiid (at plus-1) being negative, it didn’t matter.

Things didn’t start out well Tuesday, the 76ers trailing 17-4 within four minutes, thanks in part to seven points from Scottie Barnes. But the Sixers got even by early in the second quarter, going on an 18-4 run of their own, powered by six Jared Butler points.

Maxey, on a stretch of 18 straight 25-point games, didn’t score in the first half, missing both of his field goal attempts. His first points came at the free throw line with 2:27 left in the third, his first basket at 1:49 left with a 3-pointer.

Maxey started the fourth quarter on the bench in favor of Butler. He didn’t re-enter until 4:45 remained.

His shooting struggles were a big reason why the Sixers shot 6-for-28 from 3-point range in the first three quarters and 9-for-38 (23.7 percent) for the game. Maxey missed a would-be game-tying three just before the buzzer.

Embiid led the way with 27 points and 12 rebounds. But his turnover with 8.1 seconds left and the Sixers down 105-103 drew boo birds nonetheless. Paul George hit a big fourth-quarter 3-pointer, part of 14 points on 5-for-12 shooting. Kelly Oubre Jr. added 12 points and seven rebounds.

Embiid had a scary moment with 38 seconds left in the first half, getting tangled with Toronto’s Ulrich Chomche. Embiid and the rookie from Cameroon tumbled to the floor, Embiid’s left arm getting yanked under his body. He was favoring that arm as he finished out the quarter but seemed relatively unaffected after the break.

Scottie Barnes scored 33 points and grabbed 10 rebounds to lead Toronto. Immanuel Quickley added 23, and Gradey Dick had 17, including a late clutch 3-pointer and one free throw from the line with 5.3 seconds left. Barners hit Ochai Agbaji for a layup with 1:32 left to put the Raptors up for good.