Again, we had both starting CB's returning, but we were losing one of the starting strike duo. Yes, Kompany was injury prone, but so were Aguero and Jovetic. This feels like dejavu.
Put it this way, both positions were losing something. Striker was losing a starter, CB a backup. Both positions had injury prone (or deemed injury prone as the case turned out for Sergio) stars. And our defense actually got much stronger towards the end of the season as our goals dried up. I pointed all these out in many arguments I had back then.
The interest and believe that Mangala was the better choice was a carryover from the previous January window needs, when we had been scoring for fun and seemed weak on defense. By seasons end, Demichelis play had jumped leaps and bounds and Garcia was playing better. Where we had actually dipped in performance was at scoring. Post Negredo injury.
Sanchez, outside of being world's better than Mangala, was actually a greater need by season's end. But because we went in for Mangala in January and failed, folks just believed we had to have him in the summer.
Again, I pointed it out then, that if everyone was healthy, Mangala was going to be a backup his 1st season (Even if he developed into world class) on the other hand, Sanchez was going to start immediately in our attack. How is a backup more needed than a starter?