Roman Abramovich's tenure as Chelsea owner means the Premier League might have to implement tougher testing for potential owners, according to the competition's chief executive Richard Masters.
Abramovich bought Chelsea in 2003 and oversaw a transformative period for the club, who have since won five Premier League titles and triumphed five times in the FA Cup, three times in the EFL Cup and the Champions League twice.
However, Abramovich was forced to put the Blues up for sale earlier this year when, after Russia's invasion of Ukraine, the UK government sanctioned the Russian oligarch.
Todd Boehly, who also co-owns the Los Angeles Dodgers, led a consortium that eventually bought the club in May, bringing an end to Abramovich's spell at the helm after 19 years.
"It's difficult to say now, with hindsight, that it's all been good, given what has transpired over the last six and a half months," Masters said when asked for his thoughts on Abramovich's time as a club owner.
"I think if you ask Chelsea fans, they would give you a different answer."
Masters suggested that English football, and in particular the top flight, must now improve on the controls and safeguards they have in place when granting would-be owners permission to purchase clubs.
"I think the situation we ended with has given the sport some challenges we've got to meet," he added.
"Ultimately, there wasn't an owners' and directors' test when Abramovich took ownership of Chelsea, so I suppose the answer to the question is, had there been that in place what would have happened and what safeguards we need to build in for the future?
"[There is] a rolling test, yes. Prevention is better than cure, isn't it? There wasn't then, there is now, it's going to change and part of that actually is probably going to be the strengthening of the annual test."
Boehly's purchase of Chelsea went through just before the UK government's deadline of May 31, and Masters explained there was genuine concern over the club's status.
"You're in unique circumstances, nothing like this has happened before," he said.
"There was obviously a genuine concern the sale wouldn't take place in the timeframe that was available.
"That didn't happen thankfully. A lot of people worked extremely hard on it at the club's end, the government's end and [the] Premier League's end to make sure things were running as smoothly as possible. We're very pleased that it happened, obviously."
Masters' comments come on the eve of the new Premier League season, with Chelsea in action against Everton on Saturday.