He was really the number two of the first wave of TDE. A lot of folks preferred Control System to anything else they'd put out at the time.
And the fall off has been crazy. These Days and DWTW both got lukewarm receptions at best (I didn't like either project), and he's only had 5 guest appearances in the past 5 years. Zay said he was sitting in on THIB studio sessions, but this dude has just been... absent.