I suggest you to change the graphs x-axis from actual date timestamps to hours played. This would really show me where and how much I have improved or changed my gameplay because I don't play the exact amount of hours every day. Do you get the point? It makes the stats independent from real time and vacation etc. I'm sure that would be possible.
Only thing where you would want to leave the current axis layout is when you want to show hours played on the y-axis.
Edit: also, saving the selected filters would be nice.
Thats something what you have to ask in the BF3Stats.com Forum.
We can't change there anything.
Ahh that's a pity.
I added that feature to the graph.
You can switch now between Time and Date. And it remembers your choice.