That's part of it, but a big part is Pederson, and another big part is the OL.
Wentz probably needs to drop 10 lbs to be more agile, but he also needs a stable (not just good, but predictable, so he knows where the pocket should be) OL b/c he's primarily a pocket QB who can scramble but he's not a runner (lacks burst).
Peddy tried to make Wentz into a RPO QB, but Wentz doesn't have the feel for RPO pass that Foles did, and isn't the runner that Hurts is. Only a clueless HC would call RPO plays that actually had Wentz try to run the ball.
Look for Wentz to go to a HC/QB coach that'll fix his mechanics and build an offense around him as a pocket QB.
I want Pederson gone b/c he's basically a players coach who is fine with a veteran team that doesn't need to be pushed, he's liked by his players and they play for him, but he's not the brightest bulb on the Christmas tree when it comes to offensive scheming. He's the wrong guy to preside over a 2-3 year rebuild.
The primary problem this year was the OL implosion, just go back to 2017 and there was one injury (Peters) to the line, and they could work around Vaitai. This year they've had 13 combinations, so it's both a talent problem and a coordination problem. Stoutland has done a great job, but when you're starting Mailata (great talent but learning on the job, literally), Herbig and Pryor, you got problems. Next year they'll get Brooks (this is the first year in 8 years he missed significant time, he was 100% off the other achilles injury), Dillard and Driscoll back, Lane is more of a question (can the ankle be fixed or is it a degenerative condition?), and Mailata and Herbig will have game experience under their belt. So whomever is the QB will have a much better OL.