If our understandig is correct about processes which are involved, it was likly that the transition would not be as its in 1998, because the 2015/2016 Event had less powerfull kelvinwaves and since the lag counterparts are related to it, it was to expect that OHC decrease is much less and that is what we see, the nagative plume of OHC was very strong in 1998. Also to notice, that PDO take not the pathway as its in 1998, since its belived, that there are some vice/versa connections between ENSO and PDO, also here it was unlikly that the La-Nina-Development would strong as in 1998