The West Midlands is the second largest urban area in the country and
it is laid out nothing like the first. London has a centre that
everything orbits. This county has Birmingham, then Coventry twenty
miles east behaving like a separate city, then four Black Country
boroughs that run into each other with no gap you could point at, and
Solihull holding the money in between.
Google reads that geography the way a resident does rather than the
way a map does. There is no West Midlands map pack. There is a pack
for Wolverhampton city centre, another for Bilston three miles away,
another for Tipton, and they have different winners. A business in
Oldbury sits inside reach of three borough packs and ranks properly in
none of them unless somebody has set it up to.
So the first question for anything regional is not which keywords.
It is which of these markets you actually want the phone to ring from,
and whether your current setup can reach them at all.