Ranked play during preseason

I've found that I have an incredible amount of success playing ranked during the period where it doesn't matter: the Preseason. Witness my recent history: http://www.lolking.net/summoner/na/30117238#matches

I remember a similar pattern last year. Anyone else experiencing this? Any thoughts as to why? I haven't noticed a decrease in toxicity or anything like that; I do notice I seem to be carrying more but I'm not the only one on the team to do so.