In my team I have some players with very low quality (1*, 0T players from academy) to keep low the aveg. q of my team.
I had an non interesting game my in CH.L. , the last of the group games, where I had already the 1st position.
So I used my 1* GK in this game to protect my basic (and only) GK.
This GK did great and won the MoM title.
Some can say, ok, just happened.
This is from another game
this GK had zero moral when I used him and now has poor
Maybe some could say that this GK has a talent and performs good no matter his low q but this also happened in my reserve team, RINOKEROS
So, is performance of goalkeepers random ?
Maybe not but for sure GK is a unique unit of the game which has individual performance.
Some seasons ago, I decided that it's not worthy to invest in GKs.
Before, I was searching for nordgen and kept them for 3-4 seasons but now I just buy a simple GK and sell him in the end of the season.
* and of course you can see that low morale many times doesn't affect the performance of the player so don't worry much for blue packs.