Was it your first battle of the day? I took the following quote from the 'Make Sense of your Shoddy Battle Rating' thread, Hopefully it answers your question.On Shoddy I noticed that even when I won against an opponent my CRE dropped (a little: 1 to 2 points max) but I was just wondering why this could be.
Colin said:However, after you play your first battle in a day, your CRE may sometimes decrease, and that's because you have not offset the daily deviation increase yet, which is applied in the rating window after your first battle in a rating period. After you play more in the same rating period, you will always experience a net increase in CRE.