The correlation in this pair is over 90 % , positive that is, meaning they move in the same direction most of the time. The the ratio is at a certain standard deviation from the mean, you enter a pair trade with the expectation that the ratio will go back to the mean . SP and VIX are inversely correlated ,so not the same thing at all.
You can graph this for a year using FXC and FXB perhaps and see what the correlation looks like. Very short term correlation is great for very short term trading. You will see that they do correlate very closely.