I think that Isshin Kurosaki was the Captain of the tenth squad. What do you all think?

I was trying to figure out who had recently been appointed Captain and it was obviously Hitsugaya because of his young age. The fact that it says in the manga he ascended to the title of Captain could imply that he got there via vacancy and he ped the tests required by Soul Society. Urarhara says to Isshin after defeating Grand Fisher how does it feels to be a Shinigami after 20 years and his cloak implys that he was a former captain and I would really doubt that Urarhara would call someone lower than a Captain rank san. Its not crazy to believe that Hitsugaya is about Ichigo's age making him about fifteen of sixteen and Soul Society was not in turmoil so the need to fill the vacancy was not imperative and a few years ped and here arrives this young kid with white hair and lots of potential.