That doesn't really make sense with the other statistic. If 50% of second rounders are starting, but only 15% are "good" you are trying to tell me that 2/3 of people (15% being about 1/3 of 50%) who are starting aren't good... all without the article to reference what your "stat" actually came from and see if what you are saying here is actually valid. But yet they are able to spend 4 years starting, on the same team, without being replaced by someone else who comes in after them.
It doesn't pass the eye test for me.