Paddy,
I regret I can’t speak to how the PMC works in Elevate/Strava, I’m only familiar with the PMC system in TrainingPeaks. Is the underlying math the same?
Regardless, I recommend you review our blog post on this subject as I suspect the issues in Strava PMC are the same as the issues in the TP PMC. Although the blog focuses on CTL and TSS, CTL and TSS drive TSB (Form). TSB is the “fruit of a poison tree” if CTL and TSS are wrong.
And, TSS and CTL ARE wrong most of the time, until you address the issues specified in that blog. Can I request you make those changes, give it 6 weeks, and then report back your new results here.
David