But what about the other article?
Here is another article, by CFN (a more credible source out there), that studied all draft picks between 2000 and 2010.
It was distributed in April 2012 (I think, the date is on there).
17.5% of fifth rounders became starter while 11.67% made it.
Here, 2 sixths are already better than 1 fifth.
Also, from the same article, an additional 16% (equal percentage for both rounds) went on and do something (ie., becoming a contributor).
This adds even more value to the sixth rounders.