Just look at the top 100, it isn't too difficult. Just looking at #1-30, 6 of them were composite 5 stars with an additional 2 being just below at really high 4 stars and top 2 in their position.
That means that 20% of the top 30 NFL players were 5 stars, yet only .6% of college recruits are 5 stars.
So if the player is a 5 star it is more likely that he will be a great player than a 3 star. Of course there are going to be more 3 star players that are going to excel in the NFL then 5 star, there just are a ton more.
If you look at percentage # of success/# of total 5 stars that will be much higher than # of success/# of 3 star players.