I think the basic question, in regard to relative success of a football club, is "What have you done recently?"
Then take the size of the city/town with the number of seasons played in the top division of English football, the number of trophies won by that club (if you are statistically minded - not 36-24-36 - then give a 'weight' to the trophy by it's importance (PL-20, FAC-12, LC-8, Youth Cup-3 etc) & standard of competition. Then you have to consider the management of the club considering investment & stability. What about a club's history: trophies won in 19th century (Villa), prior to WW1 & 2 the post war. There's more of course …….
I've always thought Cov to be similar to Middlesboro, Southampton, Norwich. Apart from Villa (just plain terrible), Leicester (likely to be 1 season wonders) & West Brom (perennial strugglers), the Midlands is hardly represented in the PL by a team pushing for honours in the game. Maybe Cove were lucky back in the 1960's to call upon a Messiah like figure to drag the club out of mediocrity into the top division. I hate to think that we are now the equivalent & on a par with Walsall & Notts Co.