Yes, those players will train faster than last season, I have noticed that Zidane and Papaleo are both training more than twice as fast at 8* this season than when they were at 9* last season even though they are still have the same numeric quality value. If I buy say 2000 green boosters and train my players again, they may get back the 5 quality needed to get the star quality back they lost after new season update.