It's not ever a forgone conclusion with FdC. The voting system isn't proportional and the juries hold most of the power; last year everyone thought Bárbara was gonna win...only to be tanked by the jurors.
When Medo de Sentir became a hit in Portugal it wasn't obvious that Barbara was going to win. Plus, Barbara came in second with a result that could have easily been a draw.
Carolina is very different from Barbara. The most important being her song doesn't sound like a French Eurovision entry. Also, Carolina strikes a better balance with a song that has a message, with a great pop image that is familiar but not mainstream and she is currently one of the best songwriters in Portugal.
And she has a new look