Here is my best guess about what this metric is aiming for: How does the quality vs. quantity of the links to this page compare? If a page has a mT/mR score of around 2, with Trust being 4 and Rank being 2, then you're looking at a content that's linked to from great sources but isn't linked to a lot. If the mT/mR score is .5, with Trust being a 2 and Rank being a 4, then you have a page with a ton of links to it, but few that are from "trusted" sources. My guess is that the latter case might start to look like spam to Google - someone building up low-quality links (blogger comments or even the dreaded linkfarms).

I am not sure what to make of a page where the Trust and Rank are both high and the ratio ends up looking close to 1. We have one page that falls under this category - the Trust and Rank are both higher than the competing Wikipedia entry, but the mT/mR ratio is lower because Wikipedia has a lot less strong content and fewer strong links directly to that page on an admittedly niche term.