Do you have Marin's indepth analayis from "Secrets of Attacking Chess?"
I never read it, someone who has read it told me the assertion is that Morphy lost on postion but won on tactics. This really makes no sense for the following reasons. Many people consider Anderssen, not Morphy, the superior tactician. But suppose Morphy had been slightly better in this area, everyone knows that tactics flow from posisition. If Anderssen outplayed Morphy positionally, then how could Morphy win tactically against probabaly a better tactician, but even if a slightly worse one, at the very least a highly adept one? This wasn't one game, it was 11 games out of which Morphy lost only 2 - while sick and against a far more seasoned player than himself. In all those games Anderssen could only win 2 from his far superior positions??
Saying something is absolute because one analyst claims it, but ignoring most other analysts who claim something different, seems rather untenable. However, saying something is possible because of a dissenting voice would seem more reasonable.
People need to put aside their Morphy worship and admit that Steinitz would be the favorite.