Power Rankings

I'm going to put together a power rankings formula for the MVFC this year. So far I've come up with an effective, simple, formula. I plugged in last years regular seasons' stats into the formula and this is what resulted:

These power rankings do not include strength of schedule of margin of victory. I would love to include those two variables if anyone has any ideas on how to plug those into my original formula. Like I said before the formula is very simple: 

((wins* points scored)-(losses* points allowed))/games played

Anyway, I just thought to myself doing power rankings for this season would be something fun to do. I am unaware of any MVFC explicit power rankings out there (besides the GPI), so I thought I'd give it a shot. If anyone has any suggestions for a more accurate system please comment here or leave me a PM on AGS.