Interpreting Football Outsiders stats.

[Ben E Lou]

I've noticed that a number of people seemed to be confused as to what to do with this information. Based on what I can tell, here's a quick primer.

"APY" (should be ALY)
For those who don't understand the stastical explanation, the simple way of viewing this is that it essentially means the ypc that your offensive line is responsible for. Theoretically, a completely "average" back for your league would get this many ypc running behind your offensive line. Sorted by ALY, here's the current situation in IHOF:

This means that Gothenburg (with the 3rd-best KRB Pct in the league) is getting the best offensive line performance in the league currently. It means that my team's o-line is just barely above average.

RB AVG.
Worth emphasizing is that this isn't your overall team ypc, but the average ypc of your backs. Pretty straightforward. Here is IHOF sorted by that stat:

Taken alone, this stat tells me what I already know--that Frederick is getting the best raw RB performance out of their RBs in the league. Now, for the stat that confuses people...

DIFF.
The most important thing to note about this number is that it is RELATIVE. You can't just look at a positive percentage and say, "Oooh! My RBs ROCK! Similarly, you can't just look at a negative percentage and say, "Oooooh! My o-line SUCKS!!!" No, you need to take both into account. Sorted by that number, here's IHOF, and we'll walk through a few examples.



First, let's start with my Tigers. We're near the bottom. What does that mean??? It means that our running backs are doing a better job than our offensive line. That's all it means, though. By itself, a negative number in this column doesn't mean that the line sucks, that the backs are good, or anything else. It just means that the backs are doing a better job than the line. Both could be good. Both could be bad. You've got to look at where the numbers fall relative to league averages to determine where you stand. So, in this case, our 4.02 ALY puts us just slightly above the league average, meaning that the o-line is performing slightly above average. The 4.40 RB ypc tells us that our backs are performing significantly above the league average. Taken by itself, "Diff" is the least meaningful of all the stats on this page.


A few other looks at DIFF:
OAKLAND: ALY=3.63 (line isn't playing well), RB YPC=4.17 (backs performing above league average), DIFF=-14% (backs performing quite a bit better than line) This combination of stats tells us that Oakland would do well to try to improve its offensive line in the offseason.

BOSTON: ALY=4.34 (line playing quite well), RBYPC=4.69 (backs performing even better), DIFF: -8% (backs performing better than offensive line). This combination of stats tells us that if Boston can avoid it, they ought not to change a dadgum thing. They have the league's 3rd-best ALY and 2nd-best RBYPC. This is a stark example of what I mean by the Diff being the least important.

FREDERICK: ALY=3.83 (line is a little below average), RBYPC=4.72 (backs are throwin' down), DIFF=-23% (backs performing tremendously better than o-line). The Frederick backs are getting lots of yards downfield when the line springs them.

OK....now for some teams that have a positive Diff...

PARIS: ALY=3.79 (line is below average), RBYPC=3.44 (backs stink), DIFF=+10% (line performing better than backs). What does it tell us? Just that the line is bad, but the backs are worse. If Paris is going to build a decent running game, this means that they need to improve the line AND the backs.

MUSCATINE: ALY=4.2, RBYPC=3.92, DIFF=+7%. This would be a case where the line is above average, but the backs are below average. Keep the line the same and put a good feature back in there, and the Musquito running game should take off.



BOTTOM LINE
1. Look at the first two stats relative to the rest of the league to determine whether the success/failure of your running game is best attributed to your line, or to your backs.
2. DIFF cannot be used by itself, other than to determine whether the line or the backs are performing better relative to one another. It tells you nothing about how they're doing relative to the norm.

Hope this helps.

[Raiders Army]

That's a great explanation. The explanation on FO is a little less straightforward. Thanks!

[Green Caesar]

Skydog,

Thank you for the clear explanation of this. I really appreciate it.

[azjoe_02]

Much appreciated explanation!!

[JeeberD]

You calling Joey Babbage a below-average back?

[Ben E Lou]

Originally Posted by JeeberD

You calling Joey Babbage a below-average back?

2013		MUS	8	155	565	3.6	46	7	70.6
		Wk 1 - CHI		11	46	4.2	11	0	---
		Wk 2 - ROC		17	67	3.9	11	0	---
		Wk 3 - ASH		19	67	3.5	7	1	---
		Wk 4 - WIL		13	39	3.0	7	0	---
		Wk 5 - FRE		24	110	4.6	46	2	---
		Wk 6 - BKN		30	102	3.4	15	1	---
		Wk 7 - AAR		13	38	2.9	10	1	---
		Wk 8 - CHI		28	96	3.4	11	2	---