I agree that Wigan and KR are well ahead of the rest. Any team that can put three or four consecutive wins together (as Leeds have done recently) is going to climb the table as there are so many teams of a similar standard, most of whom are struggling for consistency. With three teams badly struggling in Cas, Huddersfield and Salford, any team who still have four or five games against them to play are going to flourish.
Wigan, KR, Leeds, Hull, Wire, and either Trinity or Leigh will make the play offs. Saints to miss, Wellens to go and Catalans to finish the season as basket cases if they don't get a quality coach soon.