A daft comparison to there being plenty of police for City games where there is little trouble but not for areas where there is trouble every week.
So you put the plod on Orchard Park or wherever. What l happens when Orchard Park or where-ever's troublemakers are at city or in city centre on a matchday causing bother - or in city centre on the Friday night sniff n piss and the plod are still in orchard park?