At the start, he uses realism (blue period, almost everything monochrome) and later he uses abstract (orange colours) and then to cubism style
DRASTIC CHANGE? JUST CHANGE?
PROGRESS? he wants to send a clearer message and to do this, he simplifies the paintings/style so that the message is more pure
With traditional paintings and styles, he is obscuring the message.
Art is subjective, so this is what Picasso believes so he may see it as a progress. however, from my personal knowledge it makes the message less clear and therefore could be argued that is not progress because it is not improving anything