The gist of their article is that, while the decline in income seems dramatic when considering the last five years or so, it fits very well into the long-run picture. In terms of inflation-adjusted net farm income, 2015 is projected to be very close to the long-run average. The correction we're likely to see in 2015 will be painful for many, but Brent and David show that this is really just a correction from a high profit period to a period of normal profits.
Brent and David also discuss the percentage changes in net farm income over the long run. The changes we've seen recently and are likely to see for 2014 and 2015 are right in line with the variability we've seen since at least the 1970s. As they point out, the projected decline in profits for 2015 is similar to the declines we saw in at least 3 of the last 15 years. None of this is intended to minimize the difficulty many communities will endure, but it's important to keep these things in perspective.
Like everything else I've read on Agricultural Economic Insights, the post is certainly worth a read as Brent and David do a very good job fleshing all this out.