5 or more signings is not really as drastic as it seems. This summer transfer window is really equivalent to 2 transfer windows. You have to plan for Xavi's impending retirement and Alves' departure right away as you might not have a chance in 2015. Just in the starting 11, Barca are going to need a goalie, a right back, a centre back, a midfielder and a forward. That's 5 players right there. More importantly though, Barca need to strengthen their entire squad, not just the starting 11. Who did Barca have this season on the bench to rescue them when they were struggling? Tello, Pedro and Song? lol.
Barca really need a revolution but that doesn't mean they need to deviate from their philosophy or their La Masia roots. When Pep made his in 2008, he had 5 non La-Masia starters (Alves, Abidal, Toure, Henry, Eto'o) and 2 players (Marquez and Keita) who played as many games as Puyol and Iniesta.