The cynical side of me

thinks some managers wear tracksuits to make a statement, to show they are more 'in touch' with the playing side of the game.
Wenger and Ferguson, two old timers always wear suits although I remember back in the days when we won trophies

the Charity/Community shield would take place both managers may don tracksuits or even shorts, although this 'friendly' had that sort of feel about it and that particular fixture takes place at the start of August, where (if we're lucky!) the country is at the peak of summer weather
Personally I think being manager of your club demands authority and no matter how you gloss it up a man in a suit always looks more authoritative than a man in a tracksuit.
Phil Brown obviously takes it to a whole new level with his headset, clearly he's in a league of his own. Words alone cannot express how much I loathe that man