The Costa Rica international struggled for consistency throughout two-and-a-half seasons in England, with the Cottagers disappointed with the return offered on their sizeable investment.
With Ruiz slipping slowly out of the first-team picture, he was allowed to return to Holland in January - where he has previously shone for FC Twente.
A move was intended to aid his World Cup ambitions and allow him to rekindle a faltering career.
It may be that a permanent switch is made in the summer, with Fulham still sweating on their Premier League status, but Ruiz is ruling nothing out when it comes to future calls.
He told Het Nieuwsblad: "Martin Jol, the manager who signed me, was sacked and I asked his successor, Rene Meulensteen, if he still needed me.
"I was thinking about the World Cup. I had to play, but Meulensteen made me feel as though I wasn't part of his plans.
"I thought I could still help the team, but he had other thoughts - although I still rate him as a manager.
"Was Fulham the wrong choice? No. My first year was difficult but I played well in my second season. This season the whole team was struggling.
"I still think I am a player built for the Premier League. I can't say that Fulham didn't play the football I prefer, but I can't say the opposite either. But if you are fighting against relegation, sometimes you forget to play football. Then you get typical English football, which suits me less.
"It was the right decision to join PSV. It is going well and after the World Cup I will weigh up my options.
"I don't exclude a return to Fulham, as they can still save themselves. London is a fantastic city."