He went on to win the Premier League title, Europa League and League Cup but has fallen out of favor with present Chelsea manager Antonio Conte.
A lot is down to Oscar too, as he has not always put his best foot forward in the English league.
Brazilian global midfielder Oscar is to become the latest big name to move to China in a £60 million transfer ($76m) from Chelsea to Shanghai SIPG, British media reported on Wednesday.
Last season Mikel established himself as an important player, and cemented his position in the starting XI when Guus Hiddink took charge.
This season, Oscar has found his first team opportunities really hard to come by as there are several players ahead of him in the pecking order.
Far more murkier than the gory details are what the various motivations that may be in play are for the involved parties.
Oscar is one of three big South American names to be linked to a move to China this week.
Conte allowed Juan Cuadrado to move to Juventus on loan, but chose to keep hold of Oscar.
According to Law, the Brazilian has told his Chelsea teammates that he is moving to China to join Villas-Boas, whom was appointed manager of SIPG at the start of November.
His form will suggest he may not be deserving of such high figures in the deal, but the Chinese clubs these days care less.
If and when that happens, the Times are reporting that the 25-year-old is set to be paid a staggering £20m per year - just shy of £400,000 after tax.
The Chinese league has seen an influx of big money moves for big players such as Jackson Martinez, Demba Ba and Ramires, who moved from Chelsea at the beginning of this year.
However, he is now earning £70,000 a week at Stamford Bridge.
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