I haven’t examined this issue at all, but Chris Cook tells a plausible story:

Britain’s Home Office operates a surprising policy: helping Manchester United, Arsenal, Chelsea and Liverpool to dominate football’s Premier League whilst also inflating footballers’ wages, so pushing up ticket prices. These all flow from its ill-considered immigration rules.

This would not be such a problem if the government were to confine its attention to the beautiful game. But, now, it is applying the principles that inform its immigration rules for footballers more widely. Under its newly-tightened system, companies can hire non-European staff only if they meet thresholds for skills and training to enter the country.

In football, the rules have long allowed non-Europeans to play professional football in the UK only if they have played internationally, representing a country whose national team is in the world top 70. Rich teams, such as Chelsea, can improve their midfields by hiring Brazilian World Cup winners.

But poorer teams near the bottom of the Premier League cannot shop in that market. For the most part, they are stuck with what they can scrape together from Europe. The result is that weaker teams suffer, particularly when trying to fill specialised positions – good left-backs are rare. In addition, since lousy European players do not face competition from similarly lousy non-Europeans, their wages are driven up. So, as well as making the league competition less intense, these restrictions on the supply of workers help to pump up ticket prices for ropey teams.