Actually, it's both. Paki had inferior knowledge of Aim-120 and it's working.
Alongside with jammers on Sukhoi, the low-power seekers of Aim-120 lock distance was reduced even more. Even if we assume their SAAB AWACS or F-16 can steer the missile towards the aircraft, without a seeker lock it will just bleed energy and miss the target by large margin. I suspect this was the case here.
However, their tactics of keeping Su-30s busy payed off.
Actually, HOJ doesn't work that way. Aim-120 has few launch modes, along with HOJ. If a missile is launched in HOJ, it will passively seek the jamming source target. Flaw is, after launch, you cannot change its launch mode to radar homing. So, if I switch off jamming in-between, the HOJ lock is essentially gone, and the missile is as good as free-flying rocket.
So, tactics are switch jamming from one fighter to another in a round-robin fashion or on-off jamming if it is a single fighter carrying jammer.
Essentially, PAF has shown to have poor experience and tactics regarding BVR combat. Or, we can say IAF is far more experienced in this field.
But, one thing I cannot (and neither can IAF, so expect a comeback after election
) swallow that they challenged us in broad daylight and tried to
shoot down our fighters in our own territory, while cowardly firing missiles from across the border. Wing Cdr Abhinandan was outraged when they tried to hit his wingman and chased down the F-16s across the border in a rather Rambo strategy.