My GK this season has had a 3 some 4s and a long run of 5s. Got to let him take deadball kicks to get his ratings back up. Yesterday he achieved a lofty 7Last season he had a good 7 average.
Not seen lower than a 3 for eligible game time.
I have a couple of 1* (and lower) players on my former counterattacking team that regularly achieved 8s and 9s but not any more since I've changed their playing system. Find a system that gets the best out of the squad you have and they will often get good ratings (except GKs) - but duds are duds.