This would make sense as Handsworth is pretty much half way between Villa Park and the Hawthorns. You generally wouldn't find many Blues fans in areas north of the city centre, while a lot of areas towards the west of the city (Handsworth, Great Barr, Quinton etc) tend to be a mix of Villa and Albion, that is amongst people support local teams anyway.
You're more likely to find Blues fans in areas to the south and east of the city - Northfield, Longbridge, Chelmsley Wood, Stechford etc. would be areas I'd say you'd find the highest concentration of SHA supporters.
The rest of the city beyond that is a bit of a mix really, when I was living around King's Heath and Stirchley, it seemed to be a fairly even split of Villa and Blues