I think all it comes down to is how much metal one needs to have in a prog album to consider it prog metal. Dublagent's threshold is simply higher than others'. I mean, I believe we all agree that TA has less overt metal than previous albums had.
I agree with the first two sentences, at least in principle. As to the bolded, no, I'm not sure that is the case. I mean, maybe in terms of
percentage of music if we take into account the amount of "metal" in relation to parts of the album that are...er..."not metal." In terms of raw
quantity, it feels about the same as past albums to me.
I guess mileage varies. But I will posit a theory that maybe it just
feels "less metal" to some simply because of some of the following factors: (1) this album seems much more consistently major-chord for DT, and nowadays, we oftentimes consider "metal" to be more minor-chord (or at least more angry-sounding, brooding, dark, or some other less happy emotion than what more melodic major-chord-influenced songs conjure up), (2) even the heavy songs on this album feature prominent "soft" parts, often as introductions, which can sometimes set up a false impression of the entire song, and (3) despite the metal, the album intentionally has a "show tunes" feel to it overall, which is not commonly associated with metal.