The idea from this article from a Guardian article from 2005 , when Chelsea had arguably the best midfield in the world.

http://www.theguardian.com/football/2005/oct/20/newsstory.sport11

Quotes.

The blend of Chelsea's midfield trio looks ideal.... Essien showed here that his reliability in possession, capacity to spot a killer pass and ability to run powerfully with the ball - allied to his defensive qualities - make him an ideal foil for the ever-reliable Makelele and Lampard. Between them the three can do everything. Makelele's selfless work at the base of midfield, where he cleans up so much defensively and triggers moves with his quick passing, was again evident. It was his winning of the ball and pass to Hernán Crespo that culminated in Chelsea's sweeping third goal as Essien's vision put in Joe Cole for a fine finish.

We've got our new Makalele in Matic , with his ball winning and quick passing , and Lampard was always a one of a kind player. But we still haven't replaced Essien.

Some more on the qualities that made Essien unique

Essien's driving runs bring a different element, his ball-winning adds to the solidity and his passes, which rarely leave the floor, can be devastating. His instinct for knowing when to run with the ball and when to release it stands out. That was demonstrated when he intercepted a loose Betis pass in the first half, surged forward past a floundering defender and picked out Drogba to put Chelsea ahead before anyone could challenge.

A recent link , adjusting for inflation ins previous record transfers , calculated the equivalent what Essien would cost today

2. Michael Essien Original fee: £26m (2005/06) .... 2013/14 estimate: £68.5m

Those kind of midfielders are rare and they would cost a lot .

There's a young midfielder called Pogba who has some of these attributes that made Essien great. Reportedly he's available for £60m ,the equivalent of what Essien was available for. The price is steep , but if he can fill this role for us , he'd be worth every penny. Just like Essien was.