Yes, those figures do mean something. Not everything in either direction but they do mean something. On average I'd say that the teams that make it to the playoffs are probably going to be deeper than the ones that don't. They're going to have better players lining up once the starters step off the field and those better, more experienced players are going to push around the less established guys on the other side of the line.
I think that you also have to take into account the mentality of some coaches. Are they trying to get something started early (I believe Parcells was excorcising some demons in Dallas last year when he beat the stuffing out of us while at the same time Capers was trying to evaluate talent and not much more. For whatever reason some coaches at certain times are going to want to win preseason games more than others.
Glanville always had good preseasons but never went anywhere in the regular season. He was always trying to squeak into a wild card spot there at the end so what did his emphasis on winning preseason games get him?
In short I think on average better teams win more often then not (blinding flash of the obvious) but in a preseason situation a lesser team might place more emphasis on winning and do so if they're capable of it but it means nothing once the games start to count.
It just depends on what they're trying to accomplish in the preseason game. It varies from team to team and from year to year depending on need.
Fitz makes bad decisions. That's not going to change.