It's common for a voice actor to "settle" into a role and the voice to therefore change somewhat. If Bloo is Ferguson's first role (and he is, isn't he?) it would be even more expected. I know that in the Beetlejuice cartoon (my favorite cartoon, shut up) Stephen Ouimette, the voice of BJ, started the series trying to sound as much like Michael Keaton as he could; but over time he let the character become his, and in my opinion made the character even better though his performance alone. He even started letting his background as a Shakespearian actor show through, which was even more awesome.
I mean, I can understand someone preferring an earlier version of a delivery, but...time goes on.
