Yes, it shows a Vulcan character can't carry an ep. without another character to play off of. Which is why the eps. Russ did get, he was teamed up with Neelix, Mulgrew and even Tori Petty to bring emotional value to a character that can't show it.^ Because they wanted to? Because their characters were easier to write for?
You said yourself, Exodus, that Tim Russ is an excellent actor, and I agree. He is. And yet he didn't get nearly as many episodes centered around his character as did Mulgrew, Ryan and Picardo. I don't blame that on his competence (edit: and I don't blame the other actors either, by the way), and I don't think you do, either. I think it was because of other factors. So why couldn't it be because of other factors with some of the other actors as well?
In any case, Tim Russ shows that there are other reasons besides competence why one member of the cast might not get as many scenes written for him as did other members of the cast. Doesn't it?
Besides, I already stated in post #192 that it's more than just the writing. I'm also not sure what the resistance is in noting not every actor is good in their role.