Blake was just plain awful for the Bucks - it just wasn't a good match. Like I stated earlier, some players just don't do well with certain teams. However, Blake played fantastic for Denver and did a pretty good job as a starter for them in the playoffs, where they lost to eventual champion Spurs.
Blake left when Denver signed Atkins (which also happened when he was with the Wizards, ironically). Denver wanted to resign Blake, but IIRC Blake's agent was asking for the MLE and Denver was already over the luxury tax threshold. Denver was not going to pay him that much, which I agree was high for his level of play and experience; but, that's what agents do.
I believe Blake and Prichard kept in contact during his 1 year stint in Milw/Den and we all know how Nate feels about him, so you can probably figure out the rest.