My take on this - and why I put in Mick Mars - is really that point that el Barto made. I've told this before, but I saw Sabbath in February of 94 in a club, with Motorhead opening. it was the Cross Purposes tour, so it was Bobby Rondinelli on drums, Tony Martin on vox, and Geezer was on bass. I saw Sabbath in February of 95, in the SAME club, with Motorhead opening. it was the Forbidden tour, so it was Cozy Powell on drums, Tony Martin on vox, and Neil Murray on bass.
It might have been two different bands entirely. Like night and fucking day. Geezer brought SO much to the party, and even though Neil Murray is a very competent bass player, it just wasn't the same.
It's not even "skillz"; there's little argument that Bruce Kulick and even Vin Vincent are better, technically, as guitar players, but Ace brings something intangible, and like with Geezer, the other guys play differently with them.
I think Mike Anthony is a GREAT bass player; I saw a club show with Chickenfoot and he blew me away. But he's lucky, in that he didn't have to do all that. He got a great gig, doing what Ed told him. Is Mike better than that? Of course, but they didn't need him to be "THE MIGHTY VAN HALEN!" I think Mick Mars is in that category. Does he suck? Nope (though I don't think he's really GREAT, either). Nikki wrote the songs, Vince was the mouthpiece, and Tommy was the cock. Perhaps the dynamic would be very different, and maybe behind the scenes he was a key strategist, but I don't think Motley is one bit more or less popular without Mick Mars.