Zaha's performances for Palace in the Championship led to him join Manchester United last January before being loaned back to the Eagles and helping them to reach the Premier League via the playoffs.
Some sections of the media questioned whether Zaha was fully committed to the Palace cause last season after agreeing to join United, but Holloway was at a loss to think of what more the England international could have done for his side.
"All I can talk about is how I felt when certain things were out there - that he didn't care, he wasn't putting it in and his heart wasn't with us when we were having a dodgy spell," Holloway told PA.
"It just wasn't true. He couldn't help us more if he tried - he was trying too hard. Nothing pleased me more in the final that he won a penalty and we scored.
"Against Brighton away he got two - fantastic. What more would that boy need to do for Crystal Palace if he isn't a legend already?"
Meanwhile, Holloway revealed earlier today that he made a deadline-day bid to bring the 20-year-old back to Selhurst Park on a loan deal.