Gronnemark spoke about the importance of throw-ins when explaining why he was recruited by Klopp at Anfield.
Speaking in 2024, he said: "He (Klopp) called me and said 'Liverpool have had a great season, but we were so bad at throw-ins'.
"He'd been reading about me in the German newspaper Bild and that's the reason he called me.
"When I came, data showed that Liverpool were 18th in the Premier League for throw-ins under pressure. In my first season, we improved from 45.4% to 68.4% and went from 18th to number one.
"People might think it's only throw-ins, but there's approximately 40-60 throw-ins in a match and they use up 20 minutes. It's a gigantic thing in football. People have been neglecting this for many years."
He added: "I was totally in shock when Jurgen called me.
"I was visiting a chocolate shop with my family; I saw the +44 and thought it was an English guy trying to sell me pens. I listened to the voicemail and it was a message from Jurgen. I tried to call him back, but he didn't pick up.
"My heart was just pounding... I took the call on my way home in the car, where I drove directly into a grass field when he called. He told me that he was sitting in a beach chair, reading the German newspaper Bild while on vacation in Tenerife, and he came across an article about me... he had never heard of a throw-in coach before."