As I go forward and compare / contrast the different WARs, I learn more and more about the different ways in which the WARs function. Comparing single players against the three systems (fWAR, rWAR and WARP) is great, but now it might help to look at how the systems, overall, compare.

Last week, Tom Tango requested that I break down the scores for each of the three major WAR systems by game. This would let us see (1) how WAR breaks down on a per-game basis and (2) how stable these systems are in terms of WAR from year-to-year. So I did that, at least for the past ten years. Here's what I found:

Pitcher WAR/9

Year fWAR/9 rWAR/9 WARP/9 2012 0.096 0.074 0.052 2011 0.097 0.074 0.051 2010 0.098 0.075 0.060 2009 0.096 0.074 0.061 2008 0.095 0.074 0.064 2007 0.095 0.074 0.066 2006 0.096 0.075 0.072 2005 0.097 0.075 0.076 2004 0.097 0.074 0.072 2003 0.096 0.075 0.074

As you can see, pitcher fWAR/9 stays incredibly stable from year to year. rWAR/9 stays incredibly stable from year to year. But WARP? WARP does not. WARP changes a substantial amount from season to season. So how about hitters?

Hitting / Defense WAR/9

Year fWAR/9 rWAR/9 WARP/9 2012 0.139 0.107 0.090 2011 0.138 0.107 0.085 2010 0.137 0.108 0.132 2009 0.135 0.107 0.130 2008 0.134 0.107 0.128 2007 0.132 0.107 0.127 2006 0.132 0.108 0.123 2005 0.135 0.108 0.121 2004 0.132 0.107 0.120 2003 0.133 0.107 0.121

Note: To compute this, I found the average number of PA/9 for each season.

Again, rWAR is very stable. fWAR is a little less stable, and has risen rather consistently over the last 10 years. Again, WARP is kind of all over the place. You can see an extreme change between 2010 and 2011, especially.

What does it mean that WARP fluctuates so much from year to year? Honestly, I'm not sure. It could mean that there are adjustments being made to the methodology that aren't being made to previous seasons, but if I know BP, I'd guess that is not the case. Hitter WARP cratered in 2011 and 2012, which were considered great pitching seasons, perhaps that is having a big effect on WARP?

Speaking of pitching, I noticed something else kind of interesting, and that's the ratio between position player WAR and pitcher WAR. For every system, there's a larger hitter WAR value per nine innings than pitcher value. I can rationalize this in my head that the contributions of hitters, as a whole, are slightly more valuable than that of pitchers. But look at the ratios for each system in 2012:

Year fWAR H-P Ratio rWAR H-P Ratio WARP H-P Ratio 2012 1.45 1.45 1.73

Now that's kind of interesting, isn't it? In both fWAR and rWAR, we see a ratio of 1.45 hitter / defense WAR to every 1.00 pitcher WAR. But for WARP, we see a larger ratio, a ratio of 1.73:1. To me, that looks like Baseball Prospectus's system weighs hitting as even more valuable than FanGraphs's system or Baseball-Reference's system. I'm not sure whether that's "wrong" or "right", but it's probably something that's important to know about the system in general.

Lastly, here's some data comparing the American League to the National League, for fWAR and rWAR. (Over the last few days, I haven't been able to pull PWARP from BP. I'll add it when I can.)

Pitcher WAR/9 - AL/NL

Year fWAR/9 AL fWAR/9 NL rWAR/9 AL rWAR/9 NL 2012 0.097 0.094 0.081 0.068 2011 0.107 0.089 0.082 0.067 2010 0.097 0.098 0.082 0.068 2009 0.109 0.083 0.082 0.067 2008 0.110 0.082 0.082 0.068 2007 0.113 0.080 0.082 0.067 2006 0.111 0.082 0.083 0.068 2005 0.109 0.086 0.082 0.068 2004 0.109 0.085 0.082 0.068 2003 0.104 0.089 0.083 0.068

Pitcher rWAR stays in roughly the same ratio between the AL and NL over each of the last 10 years. However, pitcher fWAR vacillates from season to season. In 2012, the AL and NL were very close together, but in 2009 and before, there was quite a bit more being generated by the AL, at least when it comes to pitcher fWAR.

Hitting / Defense WAR/9 - AL/NL

Year fWAR/9 AL fWAR/9 NL rWAR/9 AL rWAR/9 NL 2012 0.132 0.145 0.117 0.098 2011 0.139 0.138 0.118 0.098 2010 0.129 0.145 0.118 0.099 2009 0.135 0.135 0.117 0.098 2008 0.127 0.139 0.118 0.098 2007 0.120 0.142 0.118 0.097 2006 0.129 0.137 0.119 0.098 2005 0.124 0.145 0.118 0.098 2004 0.129 0.135 0.117 0.098 2003 0.123 0.143 0.117 0.098

Once again, we see that rWAR for hitters keeps the same ratio between AL and NL consistently over the 10-year period. fWAR, again, is a bit of a different story. It fluctuates from year to year. In rWAR, there's a consistent pattern that the AL is racking up more pitcher / hitter WAR than the NL. Now, I know we've all heard for years that the AL is the superior league to the NL, that's not new news. But has the AL really been at (nearly) the exact same level of dominance in both areas of the game over each of the ten past years? That sounds ... counter-intuitive, right?

And look at fWAR. fWAR varies quite a bit from year to year between the leagues, which actually makes quite a bit of sense to me. I mean, I would think that the level of competition between the leagues would vary, as teams and players rise and fall, and talent moves back and forth between teams in different leagues. But what stands out the most is that the National League has, more or less, been worth a substantive amount more hitter fWAR per game! Remember what I said earlier about the NL being the inferior league? Well quite a bit more fWAR is being assigned to the NL, rather than the AL, on a yearly rate basis. This isn't just because the NL has more teams, this is a rate basis. Should we really advocate that the NL is the hotbed of offense (yes, pitchers hitting ARE included), while the AL isn't?

Yes, this post is a bit of a data dump, but there's some use in taking a look at how these different systems work. What do you think we should do with this data? What conclusions can you draw? And is there a particular path of inquiry you'd like us to take moving forward?