Chelsea owner Todd Boehly admits Kalidou Koulibaly was a signing that could not handle the Premier League.
The veteran center half arrived near the start of Boehly's tenure for a mega fee from Napoli.
However, he was sold last summer to the Saudi Pro League in an attempt to get his wages off the books.
Per The Mirror, Boehly said: "There's no bigger sport in the world.
“When you think about just the size and scale of European football, it's just mind-numbing and there's no better league in the world in the Premier League. If you look at how these guys play, the speed with which they play the game.
"One of my players who I had a great relationship with is Kalidou Koulibaly. Koulibaly came over from Serie A (where he played for Napoli) and he told me one time, 'In Serie A, I get to think and then run but in the Premier League, I have to run while I think, and I'm still adjusting to that'."