I honestly don't find Philly's offense to be that complicated. They have talent for sure; but with Simmons' inability to shoot it limits them and Boston has great flexibility on the defensive end to force Philly into mixing it up. Philadelphia's three point shooting opens up the paint for Embiid to post up and Simmons to drive, but the Celtics are an excellent perimeter defensive team. Guys like Smart, Rozier and Larkin slip over screens used to free up Redick and Belinelli, so those guys don't space the floor as well as they did against Miami. They have enough length and hustle on their rotations so that more spot-up shooters like Saric and Covington don't have as many easy looks at the basket as they might against a less talented and poorly coached team.
Baynes did a really good job on Embiid. The strategy was to not double him in the post, and while Embiid had a good game, Baynes won enough of the battles down low to pay off risking the isos down low in favor of covering the three point shooters. The Celtics can win this series if Embiid and Simmons play really well; they can't if Philly's role players are scoring 20+ a game.
At the end of the game I thought for all their talent Philly's offense looked very basic and poorly executed. They settled for a lot of contested jumpers and tough shots in the paint; the Celtics had much better ball movement and got way better looks on offense.
Embiid looked completely lost on some defensive rotations down the stretch, including back-to-back Horford jumpers that really put the game away for Boston.