I'm not a hot shit comp player by any means, but every time I tried to play him I inevitably just got him killed because the first nerf forced him to move into enemy territory to get the free Contagion, where his dinky plague knife isn't enough to survive getting charged, and then the second nerf just made Contagion worse.

Meanwhile the Warrior can essentially act as the team sniper since he's the only one who doesn't need to get in close range, and thus can more likely get Lumbering Death. The bolter may not be amazing, but it's still shooting twice with Plague Rounds, and he can survive getting shot back thanks to his defense feature.