@GhostofCain remember we did sample quite a number of bootlegs from that "questionable" period and found no evidence of bad drums.
Also cocaine tends to make drummers better, not worse. It's an upper not a downer. Also cocaine does not hamper the digestive system the way other uppers do and it really doesn't have a prolonged effect like amphetamine, and it is the #1 drug of choice for rich people because of that. They can be high throughout the day and still have a dinner and a good night's sleep. They could've blamed anything else, and I would believe it more. Drummer takes a drug that opens up the cardiovascular system - gets worse. Sounds like The Onion article.
Anyways I think the drug/party thing was just a catalyst and that supposed Clive's unreliability on stage isn't impaired performance, but some beef with Steve and wanting to play the things your own way. It is remarkable how bandmates accuse him of not keeping it together, it means they hear something we don't, one can conclude that it isn't the basic flow and sound that Clive fucked up on stage but some sort of rhythmic cohesion they had going on, he was prone to break it and go swinging. Clive's indulgences may be the consequence of that musical rift, not the cause.
Meanwhile they had a #1 album and a great drummer nonetheless. They undertook a half-year process of making Clive replaceable. As he was drifting away from the band he was making himself more replaceable as the days pass because the authorities of the band started spending more and more time on finding replacement.
What actually happened to Clive isn't that important to me, as long as no great injustice has been done to him. This is a tough topic and we're talking about people not with us anymore. In many angles it is a fucked up discussion. But. The prevailing opinion in early days/DiAnno bunch is that Harris fired Burr because he wanted to play with Nicko. While I believe the truth to be - creative differences between Harris/Burr cannot be dealt with and became a fight at some point, Burr got distant from the band, the drugs and stuff are the cover because Maiden never talks about fights in between band members.
Actually Clive being Clive, a top drummer, prolonged his period in the band and possibly his skills might've lent him enough time to start seeing things "the Harris way". Alas it didn't happen. But if he was any less of a drummer he'd be kicked out before because you can't be a drummer in Maiden and not listen to Steve Harris.
Years after Clive has a rosy memory of the Number of the Beast (his #1 album). Old feuds are forgotten, he's ill and his old comrades come to his aid. Everything is being tossed on the table as the reason for his departure, apart from the one I believe weighs most - Clive and Maiden simply weren't a match anymore after mid 1982. He knew it and the band knew it.