While I'm pretty sure that the analysis is sound on a "making things work smoothly" level, surely the broader problem is that Labour (and everyone else) is having to play a different game on a different pitch.
It's pretty clear that someone in the SNP (probably around July 2016) realised that to get what you want is to let the other side argue politics and policy, while you hammer away at the emotional message.
So for every wavering voter who is convinced by a line-by-line reading of education policy, there will be four convinced by "but at least it's no the bastards in Westminster screwin' it up, eh?"
Until Labour (and others) can find an emotional reason for unionism to counter the emotional reason for nationalism then the nuances between different levels of possible devolution aren't really going to win their voters back.