In my opinion, the scoreboard is roughly right. Anyway, even if it is slightly innaccurate, Blitz is still the best since he is about 1000 points clear, no matter how many team games he plays
Well, if he ever starts playing solo games, we might find out. Till then, I think the jury is still out. Winning tons of games when you and a partner are both good and have a team strategy is pretty simple when you play random opponents that often don't know each other. And if one of the opposing team is a poor player, the second player can't really compensate.
Till we see a comparison of how people do when they are playing by themsleves, all we know is how they play as a team. If you think that is exagerrating, go into game finder and search active games for any General. I do it periodically, and haven't seen any of them in a solo game for ages. It's always a ton of team games, and almost always with the same partner.