That, and I also think that the current SSTs belie the fact that the atmosphere is beginning to part ways with what is a very stagnant cold ENSO event.....its almost akin to how winds transfer to the surface more readily in an intensifying tropical system, as opposed to weakening or even steady-state systems. The mechanisms that foster the development of ENSO are what also fuel the associated IOD response and couple with the atmosphere. In a season like this one, while we still have a well coupled event on paper, much of that is residual and more a reflection of what had been...kind of like SSTs being shaped by a previous H5 pattern. I think a lot of this la nina right now is merely an atmospheric imprint of the previous couple of years. At least this is how I perceived the research that I conducted on the relationship between ENSO and the IOD.
This goes along with what John is saying, although I think his attribution is probably more geared towards CC than mine.