Martinez bought a lot of shite and they all got game time except this guy. The fact that the man who bought him never played him either says to me it's simply a case of him not being up to scratch.
No Evertonian can say, with absolute authority, that Niasse is "badly, badly shite" because none of us have seen enough of him play for the Blues.
I'll admit that what we all saw at Goodison didn't look promising, however you've got to give the guy a little leeway (the team were playing poorly, the manager was a lame duck, the player had relocated to a new country and league etc.).
How you start your Everton career is not always a good pointer (Bilyaletdinov, Jo and Michael Branch would all tell you that I'm sure, as they all had impressive beginnings that didn't pan out too well).