Van Dijk was superb for Liverpool throughout the top flight campaign.
It saw the Dutchman named the Premier League Player of the Season ahead of his team-mates Sadio Mane and Mohamed Salah.
But Crooks thinks it is crucial Liverpool take home the Champions League trophy on Saturday, June 1.
“I have almost run out of superlatives to describe Virgil van Dijk’s performances this season,” he explained.
“What the Dutch international has brought to Liverpool’s defence is almost unquantifiable.
“I do feel however, that if Liverpool fail to win the Champions League, and that is by no means certain, it may hasten Van Dijk’s departure.
“Players of his class need to be playing for the best team in the world.”
Liverpool went into the final day of the Premier League with a chance of winning the title.
But thanks to Manchester City thrashing Brighton 4-1 they had to make do with second place despite only losing once all season.
Van Dijk admitted he was frustrated after failing to win the Premier League title.
“Congratulations to City, they deserved it and it was a great title race,” he said.
“Frustrated is the word [to sum up losing out]. I think we are all going to be a little disappointed because we were so close.
“But we have to look on the positive side and remember we are still in Madrid [so] hopefully we can end the season on a high – that’s what we are going to try to do.”
Liverpool take on Tottenham in the Champions League final.
It means either Jurgen Klopp or Mauricio Pochettino will secure a major trophy to cap off the year.