Arne Slot said he knew Liverpool fans would boo when he decided to substitute Rio Ngumoha in the 1-1 draw with Chelsea – but that they would not have done if they knew the full story. Thousands inside Anfield showed their displeasure when Slot took off the 17-year-old winger, who had impressed and assisted Ryan Gravenberch’s opening goal on six minutes – and brought on club-record signing Alexander Isak in his place. The Dutchman noticed the scale of the dissent but he revealed that Ngumoha had been suffering from cramp, forcing his removal, even though he he did not want to bring the teenager off. Rio Ngumoha was subbed off for Alexander Isak on 62 minutes (Reuters) And Slot admitted the boos would have been understandable if Ngumoha was removed when he had been able to continue. “Rio was not injured,” said Slot. “He had cramp before then and he went to the floor and I had contact with him. That’s why I took him off.…