It almost certainly saves space as the odd placement would be to optimize signal routing. You need a fair amount of space around a BGA to fan out all the signa

It almost certainly saves space as the odd placement would be to optimize signal routing. You need a fair amount of space around a BGA to fan out all the signals, and at $20 they certainly have tried to do this with the minimum number of PCB layers possible which makes the routing problem much harder. That being said it does look really strange.