great informative article by pat kirwan on nfl.com talking about offensive packages different teams use. some good ol x's and o's with some interresting charts using the steelers and seahawks personnel to illustrate his points. its pretty long so heres the link and an exerpt.
"Let's take a look at how much playing time players get during a season to back up just how much coaches are rolling through personnel groups. The Steelers are often perceived as a very conservative, "old-fashioned" offense, but offensive coordinator Ken Whisenhunt stresses opponents with personnel as well as any coach in the league. Pittsburgh used 11 offensive packages last season to mix-and-match and find ways to create advantages. You might be amazed to see that not one player in this group played more than 81 percent of the offensive plays. "