All the signings made sense on paper at the time.
Rodwell was young, talented, homegrown, and actually looked a player for us when he was fit. Maicon was an experienced wing-back who was clearly signed for that 3-5-2 formation Mancini wanted to use more often but then ultimately moved away from. Javi Garcia was way better than a lot of fans gave him credit for and he formed part of the midfield that won the title over Liverpool in 2014. Sinclair had just finished the previous season with 13 G/A (only two short of Adam Johnson's 15 G/A) in a promoted side and was worth a gamble at £6m, it just didn't work when he arrived. Nastasic was good, he just got that bad knee injury in 2013 after being made to play on a swamp during an unnecessary mid-season tour of Hong Kong and China.
And, honestly, in the end it didn't really matter because if those Pellegrini rumours hadn't leaked on FA Cup final day we'd have finished the season in 2nd with some silverware to go with it. And then we had a cracking summer in 2013 and won the league following season. Our one genuinely bad transfer window under Sheikh Mansour came after beating Liverpool to the title, imo - that really did set us back years and it took Pep coming in and completely ripping up the transfer policy for it to be sorted out. It made sense to get Mangala, he just didn't work out, and Sagna turned out to be a decent buy. But Fernando, Zuculini, and Bony didn't feel like great buys at the time and, looking back, deciding to completely freeze out Dzeko so we could accommodate Bony was a terrible move.