Implicit with vaal orb

Hi,

Yesterday, i'll purchase 6 unique item for vaal them and had a chance to corrupt them to +1 to Powercharge.

After 4 try, i vaal an item and the corrupt gave to me 2 implicit modifier (+ 1 to Power charge ; +2 level to socketed aura gems).

After many research, i'll see on other forum a mathématical form for calculate this, but i don't know if it's possible.

I'll want to other return for be sure it's not a bug.

Thanks for any responses.

GL Exiles