The Paraguayan international rejoined the Rovers on loan in January after experiencing difficult times with City and now Kean has left the door ajar for a permanent shift to Ewood Park.
"It was tough for Roque," Kean told BBC Radio Lancashire.
"He picked up a couple of knocks that niggled away at him. It was just difficult for him to get to full speed quickly enough.
"Being around the place and showing his quality every day in training, he showed us how good he is," he added.
"It was just difficult because he's been out so long that he wasn't at full speed quick enough to give us the impact on the pitch in the games that he played."