Major Label Debut is what that is. Pantera certainly does their best to ignore their first 4 albums. That is one of the biggest debates about Pantera from the critics. They completely changed their sound and look when they put out Cowboys From Hell. I always thought those guys were talented but didn't have an identity until Phil Anselmo came in and took control. Dimebag is certainly one of the best guitar players to ever live, but if it wasn't for Phil Anselmo I don't think he would have ever been discovered in the capacity he was.
That Damageplan album was absolutely horrible
Phil made Pantera heavy and wouldn't allow anything less than heavy. Even that Power Metal album he sang on was much heavier than the previous Pantera albums. I actually like that Power Metal album.
None the less I love Pantera, especially Far Beyond Driven, The Great Southern Trendkill, and Reinventing The Steel. But I can't give them much in the credibility department as I know they were originally a lost glam rock band until Phil Came in.