Who really gives a rat's ass about the Yahoo rating?
Yeah, The Yahoo rating is a joke, and doesn't mean a darn thing to me.
As far as these stupid commish's, you can usually bait them to allowing you back in or whattever by calling their manhood into question.
I had a league two seasons ago like this, where the commish cherry picked off of the four worst teams after I built a HUGE lead in late July. It took me 2 weeks of calling him all types of names and telling him he was a horrible fantasy player until he finally unlocked me and gave me access to those teams he cherry picked off of. I basically challenged him by giving him free reigns to whomever he wanted, as long as he unlocked me and gave me access to his 'leftovers'. Longer story short, I beat him by about 4, after being up over him by over 25 pts!
If this doesn't work, just try to team up with the other owners and work against him, if it is even possible. If not, oh well, you know what was really going on.