What these two graphs show is that Recency and Frequency both predict who is most likely to respond to this offer. The most recent and the most frequent respond better than lower ranking quintiles. The differences in these two charts, however, are striking. Look at the difference between the 5's on both charts. This is to be expected.
Recency is usually a more powerful a discriminator than frequency.
That is why RFM is not FRM or MRF or some other combination. RFM analysis is more than forty years old. Direct marketers knew about these principles back in the Stone Age. Recency, therefore, is the most powerful, and the easiest to define. The question I would like to focus on, however, is frequency.