Usually, ministry posting is about politics, not competency: a minister post would be proposed to political allies in exchange for support during the campaign. It's how, in France, we ended up with Taubira as minister of justice (here called "guarde des sceaux") under president Hollande, in exchange for the support of her radical left party during the 2012 elections. And she was mostly incompetent in that role, since she had no prior qualification, other than being a politician.