Captains are usually the most "experienced" in a team i.e. they late 30's and let themselves go Thats why they stand at the back so they cant be laughed at when they try and run.
Thats it! Us fat men would be humiliated if we played front with the exception of MarkehB.
I think it's so that from the other end of the field they look the same size as the front players....hmmmm....didn't think that one through too well, did I?....
...erm....
Maybe it's a sympathy thing. you know...the prove we're not Fat-ist. they aint no good as front players, so we've gotta put em somewhere!!