I've been using 41221v for about 10 seasons now at a point my team started struggling and I kept loosing to weaker teams even though my team was 120% quality so I decided to buy 4 key players 2 from Academy (Mc, DC) and 2 recommended (Dr, aml) and since then my team has completely changed and I won the treble last season and still on a 45 match winning run stretching to last season when I brought in these players and I'm using same formation and I still maintain same quality of 120%.these 4 players have been absolutely outstanding.
It is obvious that there is a hidden factor that makes some players perform better than others irrespective of quality so I would advise that you buy recommended players and Academy players in key positions of your squad and then u power train them and keep them for many seasons. U can also get these "hidden quality" players on auctions I've seen some of such players on this forum but they are difficult to identify and when u get a player that performs u better hold on to him for as long as you can.