Power/Ground Inductance in PCBs?

I work in PCB mfg, and a customer uses a particular footprint for a BGA device, and I'd like a layman's explanation of what they are doing. Instead of the standard "dogbone" configuration, where a straight trace connects the via pad to BGA attachment pad, they use dual arced connections (the arch is for better soldermask adhesion) in order to lower inductance for power and ground connections. Can anyone explain this in common terms?