The team in 2008 was
Valdes
Zambrotta - Marquez - Puyol - Abidal
Xavi - Yaya - Iniesta
Messi - Eto'o - Ronaldinho/Henry
Give or take, right?
So, in 2008-09 we were looking at what signings in terms of players who would be starters for us? Well, you have RB, and that's about it. So we went shopping for a starting right-back and got Alves.
So starting position, high-profile signings intended: Alves.
In 2009-10, we have the Eto'o situation, where we signed Ibrahimovic. Rest of the team was set.
In 2010-11, you have Puyol who was older and needed some fierce competition. Rafa Marquez left. So we needed another signing who could play in the first 11 at any time. Enter Mascherano. Plus, Henry was nearly done in the first 11 after a poor 2009-10. Enter David Villa.
Greatest team ever with 2 starters signed at the begining of the season. 2/2 success rate. Both of which will play in the CL final that season, seamlessly integrated in the team in under 6 months.
In 2011-12, Villa got injured badly and was never the same. Enter Alexis who was signed to provide even more competition up front (but attack was still Villa - Messi - Pedro). Plus, we wanted to sign Cesc for a long time, and we did it as well.
So, the point is most signings that were directed at improving the first 11 were successes, some became actually legends of the club (Alves, Masche, even Villa probably). The other ones were meant as back-up, or were some talents (perceived as such at least) that we took chances on.
We got badly burned on only 1 transfer: Ibra deal. And somewhat Chigrinskyi because we clearly overpaid for that dude. Should've been a 15m signing not a 28 or what it was. Rest of the transfers are on the cheaper side, for squad options.