Henry has told Sports Business Journal in a rare email communication that FSG will not accept mediocrity after a difficult season at both Liverpool and the Boston Red Sox.
Henry, who has not spoken to the media in six years, addressed mounting fan frustration across both organisations. The Red Sox fired long-serving manager Alex Cora and five coaching staff last week following a losing start to the MLB season. At Liverpool, Arne Slot's second season has fallen well short of the title-winning campaign that preceded it, with Champions League qualification still not guaranteed despite the club spending a record transfer fee twice last summer.
Henry referenced both organisations in his message, drawing on a memory from Anfield to make his point.
"Fans get frustrated. The Sox looked terrible for their first 25 games. I remember a plane flying overhead when we were beating Manchester United 7-0 that read 'FSG OUT'. It doesn't mean you ignore them — it means you work harder. You don't settle for mediocrity. You have to win."
The email represents Henry's clearest acknowledgement that the current Liverpool season has been unacceptable, even as FSG continues to back Slot publicly and is expected to retain the Dutchman ahead of next season. Slot has overseen what is being described as the joint-worst defeat record in a single season this century at the club, matching the totals suffered under Rafa Benítez in 2004-05 and 2009-10.
The situation has been complicated by extraordinary external circumstances. Diogo Jota died in a car accident in Spain in July before the season began, with the loss of the club's vice-captain and one of its most reliable forwards casting a long shadow over what followed.
Liverpool supporters also held protests over a three-year ticket price increase plan at recent home matches, with the Spirit of Shankly supporters' group leading demonstrations at Anfield and the official Supporters' Board sending an open letter to Henry.
Slot's side host Chelsea on Saturday, three points above fifth place with three matches remaining.