If you keep up with events, it is not a mystery. Russia's only AESA radar proved totally inept during Indian trials. ECM suite was stated as being wholly obsolete and not even comparable to Western systems.
I don't think that was the only reason for Mig-35s failure. It lost a canopy during tests and it's inadequate engine power was a problem too. Personally I don't think the actual reasons given to Russia are the same as what's being reported in the papers. However it was a prototype and IAF did not seem interested in one as compared to in service aircraft, maybe the Gripen NG too.
We know or we can positively guess F-16s failures, but we cannot say the same for the SH. Similarly, we don't know exactly why Gripen lost either, except that it is a prototype. All we know is they lost and the papers did not waste time speculating the reasons for the losses.
As for Russian development of AESA, we will know soon enough. The MKIs will be the first operational Russian aircraft with AESA in the near future. IAF and our internal civilian analysts will be able to tell which has the better radar, Rafale or Super MKI. Both have a similar time frame for induction too. Currently the performance of the Bars is first class. A Bars based AESA is bound to be better, if not the Phazatron Zukh AE.
Till date, only the Typhoon was evaluated without an operational AESA radar. Some general info, the RBE-2s first version used US T/R modules.
As for your cheapshot on Mig-35s ECM. The Mig-35s ECM was the only other active internal ECM kit in the competition, rivaling the Spectra. The system used is the Virgilius system made in Italy which was based on Spectra's design. Read up on ELT/568v2. However since Italy lies to the East of France, I guess it is not western enough.