It's really not fair to call JM's track sloppy, it really isn't. With that much distortion, it sounds really ugly in solo, but listen to it with the drums, and it's groovin like a beast. And that's what matters, isn't it? He plays in time, and I was very surprised to hear that he REALLY digs in, just like Geddy Lee. His playing style is really similar at times, and if you listen to the isolated Rush tracks from Moving Pictures, those tracks aren't any tighter sounding, but as a whole, it's perfect. That's the thing, it can sound sorta sloppy in isolation, especially distorted bass, but put it back in the song, and it's just wonderful.
At least it proves that they are human, even JM.