The players I'm referring to can get around their instrument. They just aren't plumbing the depths of themselves or these songs. It's not like they have to look emotional while playing from an emotionally deep place, I'm not saying that at all. Garibaldi is a great example of that.
I'll try and put a finer point on it. It's not the emotion that the player puts into their instrument, it's the emotion that flows out of their instrument that is the criteria I judge a performance on.
I used to have too much going in, not enough coming out. I pretty much got past that, with the help of my trusty recorder.
An analogy would be someone reading you a story monotone vs someone reading you a story with varying degrees of emotional intensity, depending on what part of the story they are in. As for the shy players, I'm betting they wish they weren't shy. I don't think being shy is a goal of musicians. The goal of musicians, IMO, is to communicate human emotions through their instrument, using songs as a vehicle. The ones who aren't there yet, like the shy ones, I get. The ones who know their instrument enough to express emotion.... but don't....are the ones I am referring to. Hey, maybe they can't because of their personality. Maybe they're too bunged up to let go. If that's the case then I think they should do accounting or something. I like seeing someone up there who is communicating, who is unafraid of expressing an emotion other than cool, rather than someone just standing there and playing the right notes. There's a world of difference in my mind. It's the difference between good and great.