Kinda depends on your goals. There will be people that get a high DAT but have no desire to specialize so they will coast through dental school and their rank will reflect that. People who are serious about specializing will work to rank high regardless of what their DAT was.
Even though my DAT was high, my classmates are always surprised to hear my undergraduate GPA. I'm not embarrassed by it though, I was able to become a much stronger student in dental school. I needed to, because I want to specialize. I think anyone can turn it around if they are serious about specializing. Just get into dental school first, then worry about your rank.