Sounds like Alonso is still driving the first race of season 1, no upgrades added, terrible on the straights version of the McLaren while you have developed the car through upgrades and are noticing significant improvements.
Surely if he were in the same, better version, of the McLaren, and that's assuming R&D is shared between drivers, he'd be qualifying further up?
It seems, to me, that it is one of two things;
1) R&D upgrades aren't shared between teammates and so he's stuck in the pre-upgrade car.
2) He is actually performing well/normally, relative to his equipment, and you are exceeding expectations and over performing by some margin.
I often think about it in terms of how long am I on the throttle versus the brakes and decide on downforce that way.
What I mean is Hungary is all stop-start (like Monaco) and much of a lap is spent cornering.
So high downforce, evenly distributed, is a must.
At Hungary I start at 8 front wing and 8 rear wing.
If I find I have some wiggle room I might take 1 off each.
Monza is a 2 front and 1 rear for me...the other extreme.
It is circuits like Spa, Singapore, Baku (as examples) that are more difficult to get right, as they have fast sections that benefit low wing, but they also have some low and mid speed corners and some big stops, which benefit a higher wing.
At Spa I run 6 or 7 front and 5 or 6 rear, depending on weather, strategy etc...