Yeah, pretty hard. Beyond ENSO, what kind of ENSO (where exactly are the hot/cold anomalies situated)? There's also all the other teleconnections: QBO, PDO, IOD, etc... These may very well be the tip of the iceberg as well, for if this were truly easy, then with the powerful computers and tools available we would have solved forecasting seasonal anomalies already and this discussion would be moot.
Even if this season is mostly a bust in terms of a shutout pattern, the other thing to remember is that the transition periods between pattern regimes may provide chances which have to be factored into consideration. When those transitions will happen is anybody's guess. That's why I keep saying there is a considerable luck factor involved.