I agree.
I still have a sneaking suspicion that this season's Everton is the best you'll see it for quite some time. It's got the right mix of Moyes's defensive organisation and signings, and Martinez's attacking philosophy, plus some great loan signings.
Think they'll revert to a proper Martinez team next year with all that entails.
There is a some truth to his inability to create a very stable defence (as shown this season) and that could very well be a worry indeed. But I do think that he just doesn't like the set up which Moyes have inbuilt in his players, and might instil some other defensive precaution that is different from the ones we have.
People keep ignore the fact that Moyes' Defensive Organisational plans have all but gone, we just don't have it. If you look at the current defence we have, Jagielka and Distin, and the way they play, it actually makes sense for the occasional lapses they have since they reverted to play in a very different style. Judging this side right now is not telling IMO.
I still think we will buy a new CB. Whether that will improve our defence remain to be seen, but I believe it will lead in a more positive direction. Moyes' defensive plan was quite rigid and outdated. In fact, I am appalled to see it very praised around here!