Well, unless you have a limit on innings pitched, or games started per week (you should if you have decent rules), your rules make it senseless to carry hitters on your bench. I think you are right by DL'ing Kinsler and picking up a pitcher.
I think you should also try to trade an outfielder for a closer, and depending on the free agent hitting pool, maybe deal two guys. You have good position flexibility with Zobrist, Polly, Beckham, and two UTIL spots. If you could deal two of Lee/Coghlan/Span/Pence/Ellsbury for a couple of closers, your team would earn quite a few more points over the season. Even if you have to give two of those guys to get one closer and then you pick up a setup guy off the wire, you will earn more points.
Right now, those extra two OF's on your bench serve mainly as injury insurance if one of your starters gets hurt. Those bench spots are much more valuable to your team if they hold relievers with daily lineups. Just taking the projected points at face value here, I am going to use this as your hitting lineup:
C Joe Mauer, Min C, DH 701
1B Joey Votto, Cin 1B 667
2B Ben Zobrist, TB 2B, OF 632
3B Gordon Beckham, CWS 3B 639
SS Alexei Ramirez, CWS SS 571
OF Jacoby Ellsbury, Bos OF 627
OF Hunter Pence, Hou OF 614
OF Carlos Lee, Hou OF DTD 660
UTIL Placido Polanco, Phi 2B 624
UTIL Todd Helton, Col 1B 601
Bench Chris Coghlan, Fla OF 585
Bench Denard Span, Min OF 582
DL Ian Kinsler, Tex 2B DTD 655
The average of your OF and UTIL guys that Coghlan and Span could serve as a safety net for is 625.2, or roughly 25 points per week. Assuming an average of 2 weeks missed per guy (which is a high assumption), you would miss out on 250 points from injuries to those guys. Meaning that if you can get two relievers that contribute 140 points apiece to replace those bench OF's you are carrying, you are going to earn more points as a team. This is without even considering that if one of your OF/UTIL guys were to get hurt, you will be able to gain points back easily enough by filling the injured guy's spot from the waiver wire.
This is all contingent on any sort of pitching limits you might see each week. If you have a games started or innings pitched limit, post it here and we can put that into the equation.
If there is no pitching limit of any sort, then carrying bench hitters should only be done with the express purpose of trading that player within the next few days. Bench hitters do not contribute enough in your setup to help your team win. It doesnt matter who the hitter is, if he cant crack your starting lineup, he is not worth his roster spot to your team.
Now, back to the original question regarding SP vs RP. If you have pitching limits, they will affect your optimal makeup of SP vs RP. If you don't, it all depends on how many points you can expect them to earn. His roster spot might be better used to pick up a 2-start SP every week and drop him for another 2-start guy the next week. Even a guy like Nate Robertson or a similar waiver wire player will be more valuable on an average 2-start week than a guy like Francisco.
So the next two things we need to consider to figure out the optimum strategy are weekly pitching limits, and whatever transaction limits that might exist.
Should I petition the Cafe to let me write a strategy column? I wrote before, but was tasked to write about weekly sleepers which I am not super passionate about and I didn't stick with it for too long.