I too see Han's character in Jedi as a logical evolution. In fact I could argue that he never was a scoundler by nature. His core personality was always as that in Jedi. His true character just gradually gets revealed throughout the trilogy as we (other characters) start to know him better and better.

In Star Wars always felt to me like he is just putting up an act, i.e. he made himself look tough and like someone who doesn't care. If that was his true character and if he really was in fact a scoundler, he surely would not come to save Luke in the final battle. And he most certainly would not join the Rebellion after that.

So even in Star Wars we can see that he was actually a "pussy" putting up an act. That is even more evident in Empire. And it finally gets clear in Jedi.