Thats the million dollar question because when you look in the various leagues across Europe no-one really seems to stand out. Theres a real shortage of top drawer centre halves at the moment with Stones and Otamendi as good as any pairing in the Premier League, if not Europe.
I just think that to completely demoralise the opposition and make us even stronger we need that real rock at the back, someone of similar ability to the unattainable Bonucci or Chiellini.
Even if you look at Spains big two, the German Rags and PSG none have centre halves who I would class as absolute top drawer, with Hummels and Thiago Silva probably about the best of the bunch. Pique, Umtini, Varane, Ramos and Marquinhos are carried by the attacking flare of their respective teams against far weaker opposition and aren't in my opinion anywhere near as good as proper physical players such as the Cannavaro brothers, Jaap Stam, Ricardo Carvalho or John Terry in his prime.
I trust our managers judgement and hopefully Pep has his eye on a real gem and will pull a rabbit out of the hat.