Interesting league setup - do you guys have a limit to how many years you keep a player or based on what round they were originally taken that limits what rounds you get to choose in?
I guess my thought is that I would take the most valuable player available regardless of pitcher or offense at the time of my pick. If it's a pitcher, cool, you improved your staff. If it's an offensive guy, use that to your advantage and trade for an equal valued pitcher during the season rather than take a less valuable pitcher at the draft. Unless of course the other owners have been unwilling to trade with you - then maybe I'd reconsider.
It does totally depend on who is kept/players available/ your draft positions after the 1st 2 rounds, etc., but if you already know that pitchers will not be taken in the 1st few rounds, why pick them up before you have to? Plus, if all the top pitchers are kept and you have all 2nd or 3rd tier and below pitchers left, won't there be a lot of those guys to choose from for several rounds after the 1st few rounds?
I also think that the top 100 offensive players are a lot more dependable/less injury risk than the pitchers. This too influences my thinking when I decide between choosing offense or pitching.
Again, just a thought. You definitely know your league and the other rosters you're up against better than i do so I could be just smoking crack here.