With the deal worth just £8 million, rising to £10 million, the Scot was significantly cheaper than both Salah and Oxlade-Chamberlain, and arrived from a club operating much lower on the totem pole in Hull.
The Tigers had just been relegated to the Championship, and there were question marks over whether Robertson would be able to step up to the level required at Anfield.
Those have been dismissed emphatically in the three seasons since, and now the 26-year-old is set to lift the Premier League trophy on Wednesday night after the final home game of the season.
Ahead of the ceremony, Robertson spoke to the club’s official website and praised Klopp for helping to unearth his potential against the odds.
“[He had] the faith to sign me, first and foremost, from a relegated club,” he said.
“I don’t think I got many Liverpool fans excited about my signing when people like Mo and Ox were getting signed at the same time.
“The manager saw something in me that he could develop into being a decent player and I’m glad he’s done that.
“It took me time, [first] three or four months was tough, but my relationship with him was the same then as it is now.
“He still looks to improve me every day in training and he still looked to make be better back then as he does now.
“So my relationship with him is amazing and long may that continue because he’s improved my game, he’s improved me as a person and that’s what you look for in a manager.
“So I couldn’t ask for much better, I don’t think any of the lads could, and hopefully he’s here for many more years to come.”
Robertson is just one of many who will credit Klopp as such a big influence on their careers, with the manager able to extract the best from every player who is willing to give 100 percent.
The Scot’s career trajectory, from the Scottish Third Division to the top of English football, is a prime example of the club’s transfer strategy, and how the manager is capable of tapping into potential that some may not see.
There are now no reservations over whether Robertson can cut it at Liverpool, with the No. 26 proving himself as one of the best left-backs in world football.
That makes the deal to bring him to Merseyside even more impressive, as with Kevin Stewart going the other way it turned out to effectively be a swap deal between the two clubs—with an extra £2 million to be paid in add-ons.
With Klopp “still looking to improve him every day in training,” there is scope for Robertson to develop even further—and that is a mouthwatering prospect.