The Colombia international joined the club from Porto for a transfer fee of €45 million back in January.
Diaz has looked promising in the 14 appearances that he has made for the club thus far. The forward gets on the ball and looks to make things happen.
As quoted by LFC Transfer Room on Twitter and journalist Pipe Sierra, the Dutchman said the following: "I am so jealous of Luis Diaz's lungs. His endurance is incredible. It seems that it is in his veins to press.
"He came in the middle of the season and doesn't speak the language. It took me 6-12 months to adapt!"
Anfield Watch Verdict
Kuyt has made some valid points. When you watch Diaz, he does not drop in intensity. The winger is clearly very fit, which is why he is able to press the opposition for large periods of a game.
Also, Diaz has done very well to walk into a new club/country and perform. As Kuyt has pointed out, the Colombia international does not speak English.
We have no idea how Diaz communicates with his teammates, but he still finds a way to work within the team's system. It would be fair to assume that Diaz will only improve over time.
He is only 25 years of age and arguably still finding his feet at Liverpool. There is no reason why Diaz could not represent the club for a number of years.
Diogo Jota, 25, is in the same position. Hopefully the duo can take Liverpool to the promised land in the years to come.