Most improved players?

The Edge...took a few albums before he learned to play.

John Coltrane! His standard ballads at the beginning of his career bare virtually no resemblance to where he ended up (which is on Saturn and I love it!)

Interesting comment about Fogerty. I always thought that CCR sounded like a good garage band rather than a slick polished band. However, this is what I liked about them. The music seemed more honest. What you got on disc was what you heard live. Some bands are so heavily produced and mixed and equalized that their studio work isn't what they really sound like.

I saw an interview once with Pete Townshend. He was commenting about how poor his song writing was in the past. He felt that that was one element of his craft that was improving with time.

John Taylor - sounds pretty ham fisted on some early stuff but the guy was self taught - he got better and put funk back into pop for a while nice grooves with ghost notes.