True. But how many did we sell on 2009/2010? We only sold Ibra and Maxwell. Figo retired, Crespo and Dacourt (34 yo) and Cruz (33) end of contract. So, it did make senses that we need more reinforcements that year. We can't just sell 6-7 players altogether and exchange them with 6-7 new players. Even in FM it sometimes doesn't work, and it won't work at real life. Because, it will damage the dressing room and players morale. Look at Man City, they are improving but very very very slow bcs they keep changing their squad. We can sell 3 and get 3-4 new players the most.
Edit: wait a minute. You said 6. Who is the other one? Lucio, Motta, Milito, Eto'o, Sneijder. Pandev shouldn't be included because he joined in the winter transfer not together with others. Arnautovic wasn't part of the team imo.