Why is he not a good option in your opinion?
Generally asking because a lot of people are saying the same thing as you are and I know little of him.
Martinez?
Bits at Swansea and Wigan were okay (eventually got relegated with Wigan, but won the FA Cup), but his Everton stint wasn't great after the first year.
Fans were against him in the end, his team played rather pedestrian football - and also displaying some fantastic levels of sh*ithousery to go with poor performances (poor tackles, injuring players, diving etc.).
I absolutely loathed Everton at the time. And it wasn't because they were beating us (that year we beat them away 3-2 and drew 1-1 at home - but they injured Payet in the process).
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Also, while I don't think he did a bad job with Belgium, he sort of chickened out vs France.
At least we tried to create and run the play vs France, Martinez was sort of content to let the game go by and hope for an inspired move from his stars. And a team with Hazard, KDB, Lukaku, Martins, etc... Dunno man, I thought Belgium could've done better that game.
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I cannot know right now, but I do think Barca might be a bit out of his league.
Messi is quiet, but far from easy to handle, especially concerning his BFF Suarez. Not sure how Martinez would handle the egos - and that's completely ignoring that I don't think he's a tactical genius either.
But hey, who knows, maybe he and Barca mesh perfectly and it works.