There's been a lot of talk around the NFL about defenses. Which one is the best and which one isn't? Particularly when it comes to the Patriots. So I decided to dig a little deeper into the numbers and see what I could find. Please keep in mind I only looked at the top 10 teams in PPG. To do all 32 would simply be too much time. #1 Patriots. Yes, in fact they are the best defense in the NFL, but it was pretty damn close. The Patriots lead the league in a number of stats. They are ranked #1 in DPR (defensive passer rating) and #3 in RYPGA (rush yards per game allowed). This shows very good balance on the defensive side of the ball. They also lead the league in defensive turnovers (but not turnovers per game) and they are as likely to score as any defense when the get the ball. 21 Defensive points. The most as far as I know. I didn't count STs points. They surrendered 27 REAL points putting them at 4.5 real PPG. When compared to their opponents who averaged 14.53 PPG this leads to a 6.53 basic differential and 10.03 True Differential. That was the best of any team. It should also be noted that that was potentially unfairly capped. You can't hold a team to negative points obviously. When only looking at the 4 non- shut outs vs better offenses it's actually higher. Imagine being penalized for shutting teams out! I also looked for consistency week to week as that is important. Of the 10 teams I looked at the Pats are the only team to have a good defensive performance in every game. Good being defined as holding a team to 3 points or more below their average. Okay being defined as holding a team at or up to 3 points below their average, bad being allowing a team to score above their average. That to me was the main selling point on why they were the best. #2 Bills. I was very tempted to give them the #1 spot. They have a fairly strong case for it objectively speaking. They are well balanced with having the #3 DPR and #8 RYPGA. They gave up the 3rd fewest total points and yards per game before adjustment. They were victimized by a horrible offense and bad circumstances. Their basic differential may have 'only' been 5.16 per game but their real differential is a whopping 8.16. The 3rd best.. Their opponents averaged 19.16 PPG and they allowed a true total of 11 PPG. They turned the ball over well with 8 in 5 games. A big selling point for them is their offense which often left them high and dry. They gave up a league leading 11 turnovers often putting them on short fields. They were also one of only 3 consistent defenses in the NFL. They had 3 good games, 2 okay games and no bad games. Not having hiccups and being consistent matters. One issue this D does have is they have yet to score any defensive points. Stopping the other team is great. When you help out your offense that's all the better. That was part of the reason I didn't put them #1, but not the only reason. However, they clearly deserve to lock down this #2 spot. #3 49ers. A slight surprise perhaps, but it shouldn't be too much of one. They have the 2nd ranked DRP and 5th rank RYPGA. They get turnovers at a faster rate than any other team. 11 in 4 games. And their offense hasn't helped their defense at times with sloppy play. 8 turnovers given up in 4 games. They finished 2nd in true differential with 8.45. Their opponents averaged 20.95 points and they give up 12.5 real points per game. The only reason they aren't higher is consistency issues. They have had 2 good games and 2 bad ones. They clearly are a big play defense with 14 defensive points scored, but a little more consistency is what's needed to put them on the Bills level. While I say they have had 2 bad games, those bad games could arguably be called okay games depending on how you look at them. Some field goals that were given up due to bad field position are counted against them but really only halfheartedly. The turnovers really hurt them field position wise. #4 Vikings. This was surprising for me honestly. I thought they were good but I didn't expect to put them above the Bears. The Vikings are a very solid team all around. They have the 5th best point differential relative to opponents. Their opponents scored an average of 20.32 PPG and they gave up 14.6 PPG. Putting them at a 5.72 differential. Not bad at all. While their offense didn't totally hang them out to dry it wasn't helpful surrendering 7 turnovers. The defense wasn't exactly ball hogging but so far has forced a respectable 7 turnovers. While the 14th ranked DPR and 9th yards RYPGA isn't great, considering their schedule it's pretty good. The key for them though is their consistency. The 3rd and last team to not have a slip up defensively. They have had 3 good games and 2 okay ones. No bad games. They also helped their offense just a tad with scoring 2 points. It's something! Overall I give this unit a slight nod over #5. #5 Bears. How could this Bears defense be ranked 5th?!? Well let me tell you exactly why. Honestly it starts and ends with one word. Consistency. One week they look absolutely amazing and the next week they look average. They've had 3 good games and 2 bad games. Unlike the 49ers there was little debate here. Both games were relatively poor defensive performances for a great D. The bears have given up 13.8 PPG and their opponents score an average of 19.88 PPG. This is a basic differential of 6.08 which is also the true differential. Even as bad as the Bears offense has been at times they've done very well not putting their D in a lot of absolutely horrible spots. Only 4 offensive turnovers in 5 games means the Bears have generally been put in a good spot to succeed. They've gotten a good number of defensive turnovers with 10 but with only 7 points scored isn't getting enough value out of them. That being said the Bears have done well in DPR 11th and RYPGA 6th. While if you average both teams out the Bears have done better than the Vikings it isn't by much, and in the end I think your better off taking the consistency over a marginal improvement. I don't expect this to stay the case the entire year. Info on the other 5 top D's in PPG. Titans – A very good D but with a few things that need to be pointed out. They rank 6th in PPG, 9th in Yards. They have by far the 6th best differential (same for basic and true) at 5.12. A few issues have popped up though. They appear near average both in DPR 13th and RYPGA 14th. Which is a bit odd. You would think such a highly ranked D would be top 10 in at least one. Then I noticed something VERY interesting. 1 turnover. That is all they've had to deal with all year. That makes things easier on your D by a lot when you play so conservatively. That being said, they are probably the 6th best D, but not in the same class as the top 5. 9 defensive points is nice and they showed good consistency. 3 good games, 1 okay game and 1 bad game. Cowboys. As we suspected... TOTAL FRAUDS. They have allowed 18 PPG and have faced on average opponents that surrender 17.46 PPG. A - .54 differential. That's right. This D that ranks 7th in PPG and 6th in YPG is actually preforming below average. Not only that. They aren't turning the ball over much (4 turnovers) and have of course not turned any of those into points. 1 good game, 2 okay games and 2 bad games. All over the place and completely average. Packers – A D we all like to make fun of them for being overrated, is actually a bit underrated right now. They rank 4th in DPR and 26th in RYPGA. Yeah, they can't stop the run which will likely be their undoing, but so far it hasn't hurt them in many games. They have allowed 18.6 PPG and faced a brutal early stretch of opponents that average 22.44 for game. That makes a very solid 3.84 differential (also the true one). They have shown okay consistency but nothing to write home about. 2 good games, 2 okay games, 1 bad game. So they are leaning the right way. Also the turn the ball over a lot (11) but have benefited by not being put in bad situations much (4 turnovers allowed). Also they haven't scored any points off those 11 turnovers which makes them less valuable. Chargers – Their overall numbers are good but frankly that is mostly due to 1 very good game. The other 4 games have been bad. This puts a total lie to all the good stats they have. A 1.32 differential (19.52-18.2) 9 PPG and 11th YPG. Their DPR at 27th and RYPGA at 18th also expose them as frauds. Broncos – How the mighty have fallen. These are no longer your 2015 Broncos. Even with them being 10th in PPG and 7th in YPG a deeper look is very troubling. They've had 1 good game 1 okay game and 3 bad games. Worst still. Their differential is - .28 (20.92 – 21.2). Making them officially below average. A true differential of 1.12 is nice and having the 8th best DPR is good too, even though like GB they can't stop the run 22nd in RYPGA. Lack of turnovers (3) is worrying. Overall a fairly average unit.