Dirks' OBP is only 24 points below Hunter's and thats with sporadic playing time.. meaning Hunter doesn't get on base often either, so why not let him do what he does best(drive in runs) in the 6 hole behind the 3 guys with the best chance of getting on base. It doesn't even have to be Dirks batting 2nd, but he has the best OBP of the 6-9 hitters. Dirks' career OBP is .332 while Hunter's is .335. Dirks is not a guy who drives in runs. He hits singles and takes walks and can also steal a base. Those are the guys you want on in front of Cabrera and Fielder. You want the medium power hitters(Hunter, Martinez) behind the bashers to clean up messes they can't at times. Just because Hunter hits .300 doesn't mean hes great at getting on base. As bad as Dirks has been this year, he gets on base almost as well as Torii.
Oops...should have kept reading.
I will address it from the opposite standpoint. You have to have men on in front of you to get RBIs chances, especially RISP.
Last 2 Years Men On
Dirks 340 PA 52 RBI 6.54 PA/RBI
Hunter 521 PA 138 RBI 3.78 PA/RBI
Last 2 Years RISP
Dirks 187 PA 44 RBI 4.25 PA/RBI
Hunter 312 PA 120 RBI 2.60 PA/RBI
% of Men On versus Total Plate Appearances
Dirks 45.8%
Hunter 46.1%
% RISP out of Men On
Dirks 55.0%
Hunter 59.9%
The assumption being made is that somehow batting #6 means more RBI opportunities, which isn't necessarily the case. Additionally, Hunter has seen more RISP from the #2, then Dirks has batting all over the place. Clearly Hunter is better driving in runs, but he will get the same or more opportunities from the #2 spot. There is nothing wrong with HIM driving in Jackson from 2B, then Cabrera or Fielder.
Next. As pointed out, there is a huge difference in getting on base. It isn't just the additional 13-14 times a year. It is the fact that Hunter has a better chance of putting himself into scoring position (.361 Slugging versus .474). Thus allowing Cabrera or Fielder quality RBI chances.
FYI,,,this notion is akin to dropping Victor Martinez from the #5 hole to the #9 hole, to "increase" the opportunities Miggy has when he comes to the plate. Think about that one for a minute.