The Dane was recruited ahead of the new season by Jürgen Klopp, who explained last week why it made sense for the Reds to take advantage of the specialist information he offers.
And Robertson revealed the positive impact the training has had on the team.
“We are switched on when it comes to throw-ins – everyone is in better positions that we are finding easier, and the lads’ techniques have got better,” said the left-back.
“We all got measured and I was one of the worst, but since the day he came in until now I think I’ve gained about six metres.
“We have all bought into it and we are all improving and are a lot more accurate. I think it is a positive thing and it has definitely worked for us.”
Klopp met up with Gronnemark to learn more about his expertise before employing his services with the view that ‘you cannot have enough specialists around you’.
For Robertson, if the work aids Liverpool’s ongoing progress then it will be well worthwhile.
“The manager has probably looked back on last season and it was a very positive one for us, getting to the final of the Champions League and finishing in the top four,” added the Scotland international.
“But the one negative he saw was that we surrendered possession when we had throw-ins.
“It is effectively like a pass. He looked at it and thought: ‘How am I going to change this?’ He brought this guy in and already in the first four games we have been a lot better at it.
“It is the small gains that can make big differences.”