Gronnemark is the first throw-in coach at a Premier League side, with Klopp admitting he had never heard of such a specialist coach before.
Liverpool have looked more threatening from dead-ball situations, including throw-ins, this season - the long throw in to the box has been a prominent feature of the Reds.
Full-back Robertson spoke to The Telegraph on a range of subjects, and admitted that Klopp made the Scotsman a priority to seek help from Gronnemark.
“When the throw-in coach came in I think I was the main target,” said Robertson. “The manager pulled me to one side and said, ‘you’re definitely getting help’.
“It’s the small margins that can help. People think a throw-in is not important, but how many times can it relieve pressure or start an attack?
“There is still improvement to do. Every full-back or anyone with a long throw has worked with the throw-in coach. It’s not just the person taking the throw, but the movement expected from everyone else.
“I think last season we were just throwing it five yards and asking for the return pass, so it was easier for defenders to get it back. There is a lot more thought and focus going to corners and it has worked so far.
“There have been a few new ideas. The World Cup helped. The manager was watching a lot of teams closely and thinking about what we could add to our game.”
Liverpool have looked more proficient in defence this season, conceding just four goals in the Premier League so far - a stark contrast to them shipping 16 by this stage last season.
And Robertson believes that it's familiarity within new additions at the back that has helped them go on to create a solid defensive unit.
“We have had more time to work with each other and have the additions of Virgil and Alisson. We’ve played together more and had a pre-season to work together, so that is a big influence,” says Robertson.
“It is a young back four, but also one with a lot of games and experience.
“Trent (Alexander-Arnold) has come back a different player since the World Cup. Look at Joe (Gomez). I didn’t know a lot about him when I joined, but he is an unbelievable player. We will all get better by playing more games with ‘Big Al’ – that’s what I am calling Alisson!
“If we can stay together for six or seven years we will have an unbelievable career. Don’t forget we also have players like Nathaniel Clyne back again giving us competition for places. Look at the competition at right back – Trent, Clyney and Joe can play there. That is amazing quality playing for one position.
“There are four top class centre-backs competing for two places, and Alberto and myself fighting to be the left back. We know whatever back four the manager picks we have to be at our best to keep our place."
Liverpool are currently stocked in the defensive positions, with at least two players per position able to help out.
Robertson believes that it's important to have a healthy competition for places: “Last season we were stretched in that a lot of injuries hit at the same time. Now there is unbelievable competition.
“We know if we drop below the standard required they manager has the excuse to drop us. That is the last thing anyone with the jersey wants. Those not with it are desperate to get it.”
WATCH: Joe Gomez on life at Anfield
Roberson also says how the manager asks his full-backs to get on the ball and be balanced in defence and attack, something he is still getting acclimatised to.
“Last season there were some games when we were 2-0 up and I was bombing forward and James Milner had to cover me. He wasn’t happy about it and still goes on about it! So maybe I have listened to James a bit more,” he explains.
“Hendo gave me a mouthful about that in one of the games, too. When we were 1-0 up against Brighton earlier this season - when it was not the best of games - it was about defending.
“Yes, you want to contribute to attack but I was not going to push on and risk losing the ball. Maybe we have got the level of control now where we are prepared to see out the game a lot more. So far that has worked.
“The manager is always on at me to be more involved. He wants the full-backs up and down. At times I may be in the wrong position, but he wants me to keep showing for the ball.
“We have a ball-playing goalkeeper now so you need to get used to the angles when he gives it that wee dink to the full-back. It is about being ready for that.”
Hunger for clean-sheets
The Reds conceded against Cardiff City at the weekend, falling short of an all-time club record of not conceding a league goal at Anfield.
Robertson maintains that the Reds are determined to keep a clean-sheet in every game they play, however they'll still be content if they win games 4-3.
“You could see the back four and keeper were especially unhappy we conceded. Big Al has got used to clean sheets hasn’t he? It’s part and parcel of the game, but it could have been avoided,” said Robertson.
“We want to keep a clean sheet every week, that is why there was so much disappointment last week.
“If you are gutted when you concede goal, and hungry not to, it can only work well for the team. There has been a lot of talk about the defence at the start of this season, but we need to continue.
“If we do win games 4-3, we’ll still be happy. Winning is most important, no matter how you do it. Three nil every week is the ideal situation. It’s a bit more difficult than that.
“But if you are threatening records at a club like this, it is not going to be taken as a negative, is it?”