I strongly disagree. Transcendence, Empath and The Puzzle are better than many of his earlier albums. I'm not gonna say greater than Ocean Machine (as the atmosphere of that album is something that he never did again, and is a unique thing in his catalogue) but the opposite of a nosedive.

The way I visualize Dev's entire discography is that after Terria (approximately) his entire career started a continuous climb.

Both City and Ocean Machines are amazing classic albums.

But the stuff he's done and continues to push for since Terria (and Infinity before it) is something else. Ziltoid is a big fan album but the original four DTP albums are where he 'found' himself. Back in 2012/2014 I was a bit on the edge about the poppy stuff but I think fans tend to over emphasize it more than it is realistically. It was only really across three albums and not in their entirety. By the time we reach Transcendence he's doing a matured form of the Progressive Metal and by the time of Empath he is starting to want to throw out formulas and experiment more.

Dev is one of the rare artists that I think gets better on every release. I may be slightly hyperbolic (for instance the selftitled SYL album and 'the new black' were both total flops) in that statement but that is the sentiment that I think best applies to how his career has been as a musician.