Ed - I'm pretty sure the 13 inch Dirt Stockers still use the old "good" open tread pattern that you and I love. The Hoosier catalog has for several years listed the Dirt Stockers as having the L pattern tread described as Super Chain Link. That pattern is indeed inferior to the old Chain Link pattern for rain use. However, despite what the catalog shows, every set of 13" Dirt Stockers I've bought has the "good" pattern. The last set I bought early this year was the same.
I think the newer pattern is used on 15" Dirt Stockers, but they've never updated the 13 inchers to it - thank goodness.