(Note: For more details on what "MOP" is, check here)
I'm not sure how clear this is going to be, but this is a handy reference chart on the 2009 pen usage. It lists the average Leverage Index (with higher meaning more stressful situations), games pitched, innings pitched, and their level of MOP. Low MOP levels are for guys who enter under the Bennett Rules, while high MOP levels are for the closers and set-up men. The arrows placed next to the MOP level are supposed to help with that understanding, as a green arrow implies the Rays go to this guy when ahead with red being the opposite and yellow the neutral entry point (although there's also the arrow which points at an angle too). This doesn't mean all of their appearances came in these situations, it's just a graphical helper with a rather obscure metric.
I don't have much else that hasn't been said about the pen yet. I do find looking at the IP/GP totals amusing though.