Here's a metric I just sort of made up on the spot... Since there are a lot of facets to defensive points than just how many actual points were given up, I wanted to take a look at some of those other factors. Basically, we've got defenses that score points themselves on fumble/interception return TDs, so if a defense gives up 7 points, but scores an INT return TD, it's a wash, the net scoring impact from the defense in that game is essentially the same as allowing 0 points, looking at this from a simplistic perspective. And likewise when opponents score on special teams returns or defensively themselves, it shouldn't count against the defense for "allowing" points that they really didn't allow because they weren't even on the field. As far as FGs, I think we should only count them against the defense when the drive the FG was kicked after had begun on the opponent's own side of the field. That way the defense is sure to have allowed the opponent to drive a decent amount of territory to get into FG range. I picked mid-field as a simple, relatively logical (to my mind at least) neutral point to use so if the opponent started on their own side of the field and crossed midfield, got into FG range, and kicked it, we can hold the defense accountable for allowing that, but if they started on the other side of the 50 yard line, the defense isn't quite as accountable for allowing them to drive potentially not even as far as to earn a first down before being in FG range in some stadiums for some kickers. Anyway, onto the numbers then (it's simpler than I probably made it sound with the above paragraph, haha): First of all, for TDs, I'm using an average number of points scored equal to the actual average number of points that were earned on TDs across the NFL this season: There were 1318 TDs, with 45 successful 2PT Conversions + 1318 PAT Kicks Made = 9144 Points off TDs = 6.9377845220030349013657056145675 Points Scored Per TD. OK. So, in 2015 all NFL defenses combined to allow 667 FG Drives 365 Rush TD + 842 Pass TD, but also shrank point differentials with 33 Fumble Return TD, 53 INT Return TD, and 16 Safeties. That comes out to about 9746 Points allowed by defenses in the NFL. Therefore an average NFL defense in 2015 allowed about 305 points by this metric. The Ravens defense had the following allowed: 24 FG Drives + 10 Rush TD + 30 Pass TD - 1 Fumble Return TD - 4 INT Return TD - 0 Safeties = 315 Points Allowed Defensively. So we net allowed about 10 points more defensively than an NFL average defense in 2015. That's a below average defense. I did this math manually using numbers from PFREF.com. I'd have to export the stats to a CSV and write a script to parse and calculate them if I wanted to generate an actual rankings list of all 32 teams, which I don't have time to do now, but hopefully I'll get around to that if you all want to see it.