I'm not a lawyer, and I'm especially not a British lawyer, but I do have an Athletic subscription. The article discusses a lawsuit on behalf of Primer League and mostly lower league soccer players in England around their "personal data." > More than 400 current and former players have signed up to pursue gaming, betting and data-processing companies who utilise their personal statistics without consent or compensatio…
1. There have been breaches of data protection law (GDPR as implemented in the Data Protection Act 2018), e.g. players did not consent to data transfer, the data isn't accurate, etc. and it's done on a commercial basis.
2. These breaches were injurious to the economic prospects of the affected players and therefore damages should be awarded.
I would imagine that the cause of action will be the tort of negligence against whoever sold the data on, and/or the gaming, betting, and data-processing companies. This is because they arguably had a duty of care to the players, the duty was breached, and the players suffered some harm -- based solely on the facts in this article.
Regarding personal compilation of statistics, that's fine - there's an exemption for activities of a purely personal nature in the GDPR - which is why you wouldn't get caught, but commercial exploitation of the data falls outside of that.