Outside the T14, rankings matter far less.
That said, they still matter matter a little. While employers don't rush out to see if a school is #60 or #62 in the latest rankings, the tend to know if a school is in the top 50, bottom 50, tier 3, or tier 4. This effect is magnified if you are dealing with an employer who is unfamiliar with your school. If you go to UBuffalo and you're looking for a job in Buffalo, you don't really have to worry about their ranking. If you're looking for a job in Chicago, their ranking does matter. Unfortunately, the USNWR is the most widely distributed ranking system out there, and perception becomes reality.
Don't worry too much about small fluctuations. If a school is 40 one year, then 45 another year, then 43 the third year, that's just statistical noise. Trends, however, matter a great deal. I would argue that a Penn State/ Dickinson diploma is one that is likely to appreciate in value. You have the Dickinson name (with the rep that it had in the Penn. area as a solid second tier, but had slid into third tier) combined with Penn State's massive infusion of cash and desire to make it into a national law school. It has moved from third tier to solid second tier. I would not be surprised if, in ten-fifteen (or more quickly) years, it manages to crack the top 50 (just barely, but still). That's a trend to watch. Then there's the reverse. If you're school trending downwards, that's a serious concern.
In the end, though, they're just numbers. Outside of the T14, you should be picking the school that best suits you, not the ranking.