Character Transitions

Now that I've been watching some of the really early Seinfeld's, I've noticed that there are definite character transitions that occured after the first couple seasons. For starters, Kramer was much more laid back, had the flat hair, and rarely left the house. Also, George seems to have much less self-esteem than he does in the later episodes (believe it or not). I mean, he's really quite aggressive now, compared to a guy who is about to freak out b/c he gets the answering machine (recent syndication episode). And Elaine seems to say more jokes in the early episodes than she does later. Now, she seems to be more "sophisticated", unlike her early days where she seems to be more of, "just one of the guys." As for Jerry, I really don't see much change in him. Has anyone else noticed this?