#1 Nicolás Otamendi

The Argentinian centre-back came to England having built up a reputation as a force of nature in La Liga. The red-bearded defender was superb for Valencia and was signed by former manager Manuel Pellegrini for a reported initial fee of £28.5m.
He was erratic, error-prone and susceptible to a rush of blood moment ever so often that he became a figure of fun among rival fans who saw him as the embodiment of what was termed as Manchester City’s wasteful spending habits.
His first season under Guardiola’s tutelage wasn’t much better as, after a promising start, his performances alongside that of the entire team dropped.
Now in his third season in England and second under the serial trophy winner that is Guardiola, Otamendi is looking like the defender that was consistently rated as the best centre back in the league during his time in Spain.
His tackling and decision making is much improved as he no longer dives into tackles but defends more intelligently.
Given the injuries to his central defensive partners; he has shone brilliantly irrespective of whosoever he has been paired with and can make a legitimate claim to being the best centre-back currently in the league.
His ball distribution has become much better, he is still as committed and energetic as ever and has added goals (4 so far, this season).
It is in Otamendi that we see the best example of Guardiola’s player improvement techniques.