You have played your "star" player (the one with the highest salary for 94 minutes last week, so I think GS training really did a great job on him keeping his shape at "respectable". When training GS you should not totally ignore the weekly minutes for your players. Like someone already mentioned before, GS gives a boost for your players after the normal update, and with 94 weekly minutes he would have normally ended up at average or mediocre.