Oh, you weren't surprised? Neither was I. The Astros only got two shout-outs from Mr. Research: one for having Danny Graves on the roster (in an oh-so-clever heading "Most unlikely names on spring training rosters"), and the other for this statement...
You can argue that six NL clubs (the Cardinals, Pirates, Astros, Reds, Padres and Marlins) didn't add a single impact player.
Well thank God four of those teams are in our division. And at least Stark's three most unimproved teams were the Pirates, Cardinals and Brewers.
Most improved teams in the NL? Mets, Braves, Giants.