Agents earn from transfers, but usually not from the player they represent. The payment structure explains most of what is contentious about their role.
The buying club commonly pays the commission
Although the agent acts for the player, the fee is frequently paid by the club signing him, treated as a cost of completing the transaction.
Clubs accept this because a player asked to fund the commission himself would demand a higher salary to cover it, producing the same total cost with more tax friction.
The arrangement creates an evident tension, since the person negotiating on the player's behalf is being paid by the party across the table.
Commission is calculated on movement
Payment is generally a share of the transfer fee, the player's wages, or both, and it materialises when a deal completes rather than while a player is settled.
An agent therefore earns from transactions, not from a client's contentment at a club, and a player who stays put for years generates comparatively little.
Contract renewals mitigate this, since renegotiating terms also triggers a commission, which is why extensions are pursued as actively as moves.
Representation can extend across a transaction
The same intermediary has at times represented the player, advised the selling club and been paid by the buyer, collecting from more than one side of a single deal.
Disclosure requirements and rules on dual representation exist to control this, requiring written consent and publication of who was paid by whom.
Enforcement is difficult because the parties who would complain are usually the same parties who agreed to the arrangement.
Regulation has focused on caps and licensing
Governing bodies have moved toward licensing intermediaries through examination, requiring registration and setting limits on commission as a proportion of the deal.
The stated aims are to keep money inside the game and to protect younger players who lack the experience to assess the terms they are offered.
Caps have been challenged on competition-law grounds in several jurisdictions, and the resulting inconsistency means the rules a deal falls under depend on where it is registered.
Young players are the sensitive case
Representation agreements signed by teenagers can commit a substantial share of future earnings before the player has any professional income at all.
Rules restrict approaches to minors and limit the duration of agreements, but competition for promising academy players begins early and the restrictions are tested constantly.
Clubs are exposed as well, since a player developed over years can be persuaded to leave at the point where the investment would begin to return.

