I like the idea of having more contextual information. If I’m reading an answer, it can be good to know if whoever’s written the answer knows what they’re talking about on subjects relevant to the answer and this is considerably more relevant on an individual q/a level than ‘total number of questions, answers and votes’, which doesn’t help me in determining if they’re good at [this tag]. If I’m new to the site or tag, I don’t even know how frequently people vote (there are some tags where users vote a lot and others where they barely vote at all), so even showing ‘tag score’ isn’t useful unless you have enough experience with that tag to know what a ‘good score’ would be.
What I think would be a good solution would be to show that x% of [user’s] questions/answers are above [score threshold], or something similar (like ‘so many standard deviations above/below average’) as this pretty quickly tells me if they know what they’re on about. As I wouldn’t want to bias voting based on this, I’d suggest putting this info in a ‘hovercard’ (or whatever I should call it) so that users don’t just go ‘oh they must be right, so I’ll just upvote without reading’. Perhaps alongside the number of questions/answers they’ve written in the interest of fairness. I’d further suggest that the score threshold be user dependent so that we can differentiate between people who e.g. consistently get ~50%, ~70% and ~90% score thresholds as saying ‘90% of posts above 90% score’ and ‘90% of posts above 70% score’ are different things.
Perhaps an alternative to the above would be the same, only instead of using score thresholds, use the user’s average score.
Outside of the context of questions and answers, it’s useful to know other things (are they good at flagging?, are they good at editing? etc.) but the only way I can think of having this sort of information without having an overly big usercard (that takes up too much space) would be to have badges.
So, my (current) solution to this would be to have a usercard with user-selected badges (and rank level?) displayed, that on hovering-over brings up a bigger version of the usercard that displays the number of questions and answers that user has posted both on that site and in that tag, alongside either the percentage of posts they have on the site and tag above some (user-dependent) score threshold or the average score they have on the site and tag.