Barcelona offloaded Suarez in the summer, with the Uruguayan joining their La Liga rivals Atletico Madrid.
It was, by no means, a popular decision, and, with the benefit of hindsight, it is safe to say that the Blaugrana made a mistake by selling the attacker. Suarez has been impressive and crucial for Atletico Madrid, who sit top of the La Liga table.
The 34-year-old has scored 16 goals in the La Liga this season, and only his former team-mate Lionel Messi have managed to bag more.
Forlan claims Barcelona's decision to sell Suarez had nothing to do with his performances on the pitch and believes it was a 'huge mistake' from the Catalan outfit's part. "Of course it was a huge mistake. As soon as Barcelona said he was for sale, I knew it was a mistake," Suarez told AFP [via Goal]. "All I know is it wasn't about his performances on the pitch.
"I messaged him and said, 'Listen, you're not the first and you won't be the last. You have to keep being yourself. You don't have to prove anything to anyone so just keep doing it at Atletico Madrid.'
"But when you get punished for something you didn't do, when you're still in great shape, playing well, of course your aim is going to be to show that you can still perform."
Forlan also drew parallels between how Real Madrid struggled when Ronaldo left and how Barcelona are struggling in the absence of Suarez. He said: "Barcelona are missing Luis, it's like when Cristiano Ronaldo left Real Madrid.
"It was not just Cristiano Ronaldo leaving, one of the best players in the history of football. It is 50 goals leaving as well.
"So if you sell a player like Ronaldo or Suarez, you have to replace them with two players and then there's risk because they have to adapt.
"As soon as Cristiano left it was never going to be easy for Real Madrid and for Barcelona now it's the same."