Since your CPU usage is so high and your GPU usage so low, plus a 7970 should be able to run the game on ultra, I would recommend upgrading your CPU as soon as you get the cash. However, keep in mind, BF4 is still optimized and buggy, as when I play with an FX-6350 OC to 4.4 GHz and GTX 770 OC to 1280 Mhz core, I still have erratic framerates and weird dips.
Have i3 and gtx660. When low settings in BF4 single player cpu usage is like 75% and gpu usage is 50%. Same happens in many other games, f.e. in league of legends cpu usage is like 45% and gpu usage is 35%, luckily that is enough for 120fps@1080p. Either there is some additional bottleneck cause or then its just a software matter that has something against high fps. Can get the usages go up when turning settings to high, but would prefer the smoothness.
Luckily in some games like the newest Dead space the fps still goes really high when lowering the settings. Try tweaking settings through console or config file as it may include additional variables that are not found in the game options.