Ramadan has started so it will be having an affect on the number of cars available.
Always better to use the City app and register your credit card or Uber (not that i like Uber), find yourself a pub, wait it out and then when your taxi arrives you don't need to pay as its automatically taken by the app. Its also a record of your route so if the driver took a much longer route, than the most direct or somehow overcharged you, then you can give feedback and get your money back for the extra. I did this with Uber in Dubai.
Although saying all that, trying to get 25,000 fans home late at night is always going to be a logistical nightmare.