No, I know that most studios aren't co-located with their transmitting antenna. However, based on the incorporated lines of Arlington, I think that antenna is still within city limits. If that map you posted is where the antenna is located, it looks like Arlington to me.
In any case, it can't be more than 10-15 miles away from the studio, and if farther west than the studio, it only makes my point stronger, in that the WBAP listening range extends from that point all the way east past Tyler even in the daytime.
I live in College Station, about 200 miles or so away, and still listen to WBAP. I can catch it all the time whereas the Houston stations are static always.