Currently distance from Corps HQ to their on-map units does not matter for leader's raitings.. Let's say you've Corps HQ and their division in same hex and move this HQ to somewhere far away (e.g. to New Zeland). Leader's raitings for this division will not change.
But if you move next HQ in the chain of command (e.g. Army HQ) more closer to on-map unit you'll get some additional % for raiting.
This is affect also Air component. E.g.if you want to get additional % for Air raiting for some Air bases during AF bombing on 1st German turn you can move closer Luftflotte Hqs (Army level Hqs for Airforces).
This is mainly affect Soviet side because during summer 1941 starts from July there is happens auto-disbanding Corps Hqs. So Soviet player not only loses one level for the raiting checks but also have to keep Army Hqs in 4 hexes away from their on-map units. Because if you move this HQ to one more hex you'll lose some % for raitings (sometime up to 10%).
Exampe 4-5 hexes difference:
At start of GC we have SS division directly assigned to 4th Panzer Group.For purity of calculations let's move AGN and OKH Hqs to hex with 4th Panzer Group HQ. Now numbers of raitings for SS division:
4 hexes from Hqs – 56,8-82,9-94,1-78,0-81,9
5 hexes from Hqs – 49,0-73,6-86,3-67,8-72,4
These things looks a bit disbalanced and sometime even absurdly and funny.I hope that something can be reworked for this “strange” mechanics.
For sure unlimited distance for Corps Hqs must be restricted. There can be added additional distance for some Hqs (e.g. for Panzer Corps,Panzer Groups,Tank Armies). Leader's Initiative can be added for the calculation of the maximum distance.
Air forces can have separate formulas/mechanics for these calculations.
Also for calculation “on-map unit – next Hqs in chain of command” need to count only distance between Hqs (if we calculate raitings for on-map unit after failing 1st check). I want to say if we have the chain “division-Corps-Army-Army Group-OKH” and for some reasons need to calculate raiting for division – Army(or next Hqs), than need only count distance between Hqs.
And sorry my English so specific =)