Originally Posted by vaticanplum
So...is anybody going to answer my question about stats relative to a roster? I would just like to know if it exists. Or is impossible to develop. Or is a dumb idea.
First, it’s not a dumb idea. Your question speaks to the heart of many debates that are had on the ORG. Intuitively you’ve put your finger on exactly what sabermetrics has been building toward since Bill James started writing about baseball. Fortunately, not only is such a system possible, it already exists! An explanation is below.
Originally Posted by TRF
This was posted a few pages ago, and should be addressed by both sides of this argument.
I absolutely agree because this is a central point that must be addressed when discussing the proper way to valuate players-it’s the ultimate sniff test. In other words, does the approach allow meaningful discussion to be had regarding a player's true total worth and does it relate that worth to its impact on the team’s fortunes on a global scale (i.e. does that production relate to a team’s real runs?). Ultimately, that’s the gold standard concerning usefulness. Here is VP’s original question in the post referenced above:
Originally Posted by vaticanplum
This article actually kind of gets to the heart of a major statistical question I have. And I hope this doesn't sound too simplistic, but – are there any stats that successfully and thoroughly take into account a player's value in the context of a given team? Because when I find myself not totally agreeing with the conclusion a set of hard and fast facts put in front of me, this is usually the element that I find is missing.
The answer is absolutely there are stats that successfully and thoroughly take into account a player’s value and places it in the context of what it means to the team…. The system is WAR (wins above replacement)
and its freely available at fangraphs.
WAR calculates marginal wins (wins above freely replaceable production) by using wOBA as the run estimator for offense (a metric that readily converts to runs), UZR (ultimate zone rating; a play-by-play based defensive metric) as the estimate of defensive value, and FIP (fielding independent pitching; estimates a pitcher’s true performance by isolating his peripherals, i.e. things he can control) as an estimate of pitching win value. As a matter of bookkeeping the offensive value provided by pitchers is lumped in with position players. So all phases of the game are measured as a position player's WAR consists of offensive value + defensive value and Pitching War consists of the value pitcher's provide while on the mound. Team WAR is then the sum of Position Player WAR and Pitching War. Importantly, again, both WAR and the individual component metrics are available for free at fangraphs so the whole system is readily accessible for fans to use and to test
In several posts in this thread, I’ve explained the approach that WAR uses and why it should be considered the most appropriate way to valuate players so I won’t dwell on that aspect. Instead, I’ll focus on the part of your question that speaks to the heart of the issue-how well does WAR relate back to the team on a global level. In other words, how well does WAR correlate with “real runs”. By answering your question, such criticisms as the following can again be addressed as well:
1) defensive metrics do not correspond with reality, or
2) defensive metrics substantially inflate the value of defense, or
3) expressing player worth in terms of marginal value is inappropriate because while it may suggest something about dollar value, summing offensive runs plus or minus defensive runs does not related to the net runs that a player created/cost his team.
So in order to test whether summing offensive runs and defensive runs relates to the net runs that a player created/cost his team, I calculated the strength of the linear relationship between team WAR and pythag record (i.e. calculated the correlation coefficient) by regressing total team WAR to pythag wins for all teams from 2002 thru 2009 (the years in which WAR is available from fangraphs). Since WAR is expressed as marginal wins, 47 wins were added to the total WAR for each team so that total WAR and pythag wins could be directly compared. This is because 47 wins represents the expected number of wins for a team comprised completely of replacement level players (replacement level winning percentage=.29 so 162*.29=47 wins). Here are the results by year and for across all seasons:
WAR vs pythag Win
year corr coef
These results indicate that when looking across all years for which WAR data is available, WAR gets us 92% of the way to the predicted pythag record. WAR correlates to runs better than OBP and SLG and approaches the correlation of OPS or RC to runs even though admittedly WAR still has room for improvement from a defensive standpoint. In other words, WAR correlates very, very well to “real runs”
. Clearly the WAR system of player valuation adds up extremely well at the team level.
Here’s a break down of the NL central over those years providing a look at how well WAR has correlated with the fortunes of our beloved Reds at the actual run level:
team Pythag WAR
cards 707 674
cubs 660 660
astros 659 649
brewers 586 595
reds 562 550
pirates 562 551
Clearly WAR has captured what has gone on in the NL central this decade very well. For instance, looking at the Reds over the last 8 seasons, WAR has gotten to within 1 win on average of their pythag record.
So WAR allows us to calculate total value for a player on a scale that permits comparison to every other player in the league in an apples to apples fashion and these player values can be used to directly gauge the player’s impact on his team at a global level as Team WAR directly correlates to a team’s RS/RA (runs scored/runs against). What’s more, WAR values also correlate directly to market values as explained in earlier posts.
The WAR system is rooted in reality, allows player valuation to occur on a scale that was previously impossible and it allows such discussion to be had in the context of market value as well. I can’t think of a better way to answer the question of player impact/worth or a better tool to evaluate roster formulation decisions.
Again, WAR and defensive metrics pass the sniff test as they reflect "real runs" pretty closely
While defensive metrics are not prefect and they certainly will be improved as new technologies such as hit f/x allows such metrics to address the issue of quality of chances better, generally, the notions that defensive metrics do not correspond with reality or that they substantially inflate the value of defense or that the summing offensive runs and defensive runs does not relate to the net runs that a player created/cost his team have to be rejected as gross exaggerations of the weaknesses of the approach
The WAR approach is not perfect-like all metrics, there are limitations and weaknesses. However, that said, the WAR approach not only passes the sniff test its ability to relate player worth back to the impact such individual worth has on the team makes it the best (actually the only) metric currently available for addressing many of the issues we’ve talked about in this thread and daily on the ORG.
Given the correlation of WAR to team wins, it's not compelling to argue that WAR is divorced from reality....