Owen's death was particularly horrific because it came out of nowhere.

Best I can gather about Warrior was that it was similar to Eddie in that it was related to cumulative damage from substances he took earlier in life.

Yeah, supposedly a few people had seen him the day before he died and reported that he looked to be in discomfort or pain and was sweating a lot. People at his last RAW appearance also said that he appeared gaunt and had difficulty moving around. Sounds similar to what happened to Randy Savage... the old heart just couldn't take all that abuse.