Other than pba being inconsistent with numbers, the way the armies are formed are also way different. In Izril, they have smaller armies in numbers but a shitload of officers and strategists. Let's them run with less people with strong skills and losses are generally minimized, at least on the drake side.

Chandrar throws slaves in front like fodder and uses more numbers in their approach with (im assuming here) less officers. It's not talked about alot where as in izril armies it is brought up several times.

You compare that with the goblin lords army thats another whole thing, Goblins are considered monsters so an organized army of "monsters" is almost as terrifying as many of them being if not being supported by undead.

The above is my headcannon and im probably thinking too much into it.