Frankly that's Barca and Real hype machine. Most years the bdo winner was the guy with most trophies, particularly in Euro and WC years.But in those years leading up to Messi/Ronaldo duopoly, the Ronaldo and the Cannavaro were exceptions rather than rule, as I can see.
Take '05 as an example: Ronaldinho wins it when Barca's only trophy is a fairly run of the mill title. They went out in the R16 of the UCL. He beats Lampard - the best player on a team which dominated its domestic league like never before, and made the UCL semi - and Gerrard - the best player on the team which won the UCL.