The amount of media money can not be influenced by an agency; they are dependent on the league positions (over several years).
Ticketing is also largely dependent on the strength of the club (and, of course, on the opponents). By improving the image around the club, e.g. In the stadium, however, ticketing can be positively influenced within limits.
The leverage for a brand agency lies in sponsoring: the more valuable the image transfer for a sponsoring partner is, the higher the revenue from this area.