Should have addressed the full backs situation a long time ago but seemingly Mancini and Pellegrini were happy with what we had. Txiki can't force players into the team.
Nearly every signing he has made in my mind has been with good reasoning, we have overpaid in some situations but we haven't bought out right poor footballers. He doesn't dictate if the player is going to settle and play well in the prem.
He has done a good job with selling players for the most part as well, look at the deal we got for Rodwell and Negredo. Hopefully that continues this summer when we move on Mangala, Nasri, Bony and so forth.