DT was incredibly successful in the public eye with MM.
Ticket sales would suggest otherwise. Their commercial peak was the start of the RR era, and since MP left it's been steadily declining.
I was talking about the Grammy win and three overall nominations.
I guess there's a few metrics one could use to gauge success. I personally find it hard to use the Grammys as one, but hard to also just completely shake it off. It's not meaningless even if they had no business (IMO) winning that, but I feel the same way with Metallica this year getting the metal performance grammy. It was not worthy song and felt more like an achievement award than the song nominated actually being a great song. (I will say, The Alien is MUCH better than 72 Seasons).
Anyway, one metric could also be album charting positions.
BC&SL is DT's best charting album at #6 and they have charted basically worse each release since then including #52 for AVFTTOTW which would be the worse since ToT.
Another and maybe the most important, IMO, would be ticket sales and attendance. That has been very hit or miss since TA tour. Seems the first legs do well, the second legs do poor in the US. However, they basically play the same spots they have since the SC era (basically since I started going to their shows) from what I can tell. I do think, on average, attendance has gone down though.
So I actually would say DT have been on a downward stream since TA, but it hasn't been some complete failure. A grammy, some very well attended tours (basically the tours where they did I&W and SFAM in full did really well), and they are still selling albums. Still some posiitves here, but hard to ignore some of those really bad tours.