1) Mannion was on the Rams in '17 and '18 when the offensive system was built around Gurley.
2) The Rams offense in '19 and '20, (when Mannion wasn't there), was built around shorter passing and more 12 personnel because of blocking problems and other issues.
3) The verbiage has almost certainly changed so whatever Mannion knew then will be out of date.
4) Mannion may not even remember what the system was in '17 and '18.
5) Fans don't know whether the Rams system was Waldron's or McVay's.
6) If it was Waldron's system he's going to have to alter it anyway since McVay already knows it and it doesn't fit what the Seahawks offensive players do best.
7) Bortles is/was a better QB, he's vastly more experienced, he's available, and his knowledge would be more relevant since he was with Waldron in '19 and '20.
If Mannion helps then good luck to you guys. It's hard to see what help an immobile check-down QB can provide.
Already stated he remembers and knows the system and has been a big help out of the gate.
So try again...................
It's McVays certainly, on this team it's Waldrons with adaptive aspects of Waldron and Russell's skill set, will be very much the same in many aspects.