Can Willian fit in at Chelsea? He can bully a Chelsea defender, so yes.
Willian was a player that Chelsea were definitely looking at in the January transfer window, with AVB admitting the Brazilian was one of the players that could come onboard the Project and add more dynamism to Chelsea's wing play. The Shakhtar player probably foresaw the sinking ship that was AVB's Chelsea, but the deal mainly collapsed because Chelsea weren't willing to pay the twenty million euro asking price for the player, with AVB claiming that Willian was a short term option where Chelsea were looking long term.
The best thing about that saga was that Shakhtar as the selling club were very open and transparent in their communications over the player's future - I've never seen more clear statements about a transfer rumour - and their coach Mircea Lucescu has been talking again, with the Telegraph reporting the following quotes:
"They have to pay the price because we bring the players here at 17 or 18 years old. We pay a lot of money because they are talented players and we bring them up. If Chelsea pay his [asking price], I am not against letting my players play for the big clubs. If they pay the price, he can go. If not, he will remain here because he has another two-and-a-half years on his contract."
That quote has been edited by me personally, but the bits I've taken out simply talk about the pile of youngsters in Shakhtar's team and how they represent good value. Therefore I really can't understand how the Telegraph is running these quotes with the line that 'Willian is for sale'. It may be implied that Shakhtar may be willing to let their prized asset go, but that's the case with most players - all have a price. The quotes simply suggest that Willian would be allowed to go into talks with Chelsea if Chelsea paid the money Shakhtar ask for. That's no big surprise.
Whether Chelsea actually want Willian any more is a different matter. The squad hasn't changed since we last mulled over whether to sign him, which means he probably would still be a viable choice to slot in as a new winger. It's more or about what the new manager wants from his squad and want signings they want. Willian was a pretty good player for the system AVB presumably wanted to introduce, but every manager brings their own ideas about tactics and system.