Over the past week my stats have taken a beating and I've been trying to determine why.
I think the main reason is that I've switched from a suite of ships I was quite comfortable with, the IJN Nagato, Hiryu, and Kuma and the USN New Mexico to a suite of ships that I'm still getting used to: The IJN Amagi, Skokaku, and Furutaka, as well as starting up the new German and Russian lines.
While my stats with the Amagi are comparable or better than the Nagato, the stock Shokaku and Furutaka suck badly; the former with tier VII planes was facing tier VIII and IX planes in some battles as well as tier VIII and IX ship based AA, while the latter just plain sucks compared to the upgraded Kuma with guns that rotate slow and had a 22 second reload (upgraded guns I just got and are better at 15 second reload). So those ships have hurt my stats as I get used to them.
For the new German cruisers, I've been performing well or extremely well in games (well above average according to warshipstats.com) but in the low tiers you have very little control over the success of the team as a lot of players just don't know what they are doing yet.
And of course, since I've been doing a lot of low tier Japanese and German and Soviet ships my average damage stat drops as I'm not doing high tier battleship and carrier damage as much.
In other words, I hope its all in good time that my winning percentage climbs back to the 52% and beyond mark, but really I don't care as long as I have fun.