Think this is the main issue.
As a team, I think we can all say we're at our best when we either a) counter attack (Sotton, Stoke) or b) play crisp passes around the edge of the box if a team is bad/stupid enough to allow us room (Villa, Sunderland, Newcastle at home etc.)
At home a lot of sides do come and sit back against us which I know is nothing knew, and it's a concern that we/Martinez haven't yet identified a way of breaking those sides down.
One thing that seemed to have helped at the start of the season was playing Kone in that wide forward role, but his form over the past two months has been awful.
So, like you said, I think it's pretty plain to see where Niasse will fit in in terms of being a starter for the rest of this season. We have Cleverley there for other games where we need to counter, and Kev as well, if the manager does use him - which I think he will at the weekend.