Rating Fluctuation

I dont know exactly what it is lately but my rating on Pogo has been fluctuating dramatically. It seems as though some 1700 players are incredible while others would be more suited with a 1500 rating. Maybe its the inaccuracy of Pogos rating system showing through. Ofcourse I understand that some play thousands of one minute games to boost their rating or only play lower rated opponents. But most seem to play against equally rated competition. Often when learning and experimenting with new positions and ideas my rating dips and then charges ahead higher than ever a couple weeks later. I suppose this is the usual learning curve. Over playing might also be the answer. My brain is good for two or three hours of chess and I tend to win the first two games no matter who the opponent, but after the first two I lose more and more consistently that day. Their are so many factors to calculate what makes someone play at one level or another it seems to become an aggregate mess when deciphering it all. Just some thoughts on it....