Pitching Winning Percentage and fWAR

I have been super busy with work and life in general and have neglected writing far too much. This afternoon I had the time to have a little fun with excel and the wealth of data that is Fangraphs.

I have always been curious how much winning percentage is associated with fWAR and decided that now would be a good time to take a look. I pulled the data from the last 3 years for pitching seasons with at least 100 innings thrown. I then plotted the data and took a look at the correlation.

So I proudly present the correlation between fWAR for pitchers and Winning Percentage:

As you can see from the scatter plot there is some positive correlation between winning percentage and fWAR but it isn't super strong. Excel told me that the correlation to about 0.49 which makes sense.

A high winning percentage usually means that a pitcher did well as does a low winning percentage usually means that a pitcher did poorly but this is not always the case and in the data set that I have here it seems that high winning percentage is more often than not a a false signal for a good pitcher.

Here are all the pitchers who had a winning percentage of 0.6 or greater with at least 100 innings pitched:

We essentially see the whole gambit of pitcher quality here from MVP caliber seasons to a season of below replacement level performance with almost no observable trend that a higher winning percentage leads to a higher fWAR.

So in the end this was a fun little experiment. We found that there is a relationship between winning percentage and fWAR which makes sense but that it really doesn't tell us more than what we already knew, that good pitchers will tend to have higher winning percentages but that doesn't mean people with low winning percentages are bad or that pitchers with high winning percentages are good.

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Giants Case Study: The Predictive Value of Wins Above Replacement

There was a comment that was posted yesterday on the post "Did the Giants' Front Office Make the NL West Race Closer Than it Needed to Be?" that got me thinking. The comment was about how good of a stat wins above replacement is.

The comment came from Greg Wurz writer of the of the blog IN THE SHADOW OF BONDS, he said "I really don't know how much stock you can put in WAR."

So this afternoon I am trying to give Greg some piece of mind to how much stock can be put into WAR. I pulled the WAR Data for the Giants (I would have liked to do every team but I do have a day job and only an hour for lunch) and compared that to the Pythagorean Expected Wins and the actual wins for each team.

The Fangraphs data goes back to 2002 so this is the starting point and I looked at through last season (I didn't include this season because it isn't quite complete yet and I wouldn't want that to interfere with the results.) so a total of 8 seasons.

Here are the results:

	WAR Predicted	Pythagorean Predicted	Actual Wins
2009	82.9	87	88
2008	76	67	72
2007	77.4	77	71
2006	78.2	76	76
2005	74.8	70	75
2004	88.9	89	91
2003	93.3	94	100
2002	101.6	99	95

Just looking at things with the naked eye suggests that they match up pretty closely. When you do a correlation you can see that both the Pythagorean and WAR predicted wins are highly correlated.

	WAR Predicted	Pythagorean Predicted
Actual	0.897051278	0.927742018

For a WAR even with the known issues a correlation of nearly 0.9 is very good especially when anything around 0.8 is considered to be strongly related. WAR can be improved especially in the measurement of defense and base running and even context specific results but even without these improvements it gives very robust results.

Fangraphs did a similar comparison looking at just last year's numbers and found very similar results of a correlation of 0.83. With that said I think that using WAR gives valuable information and I think that you can put a fair amount of stock into it.

Did the Giants’ Front Office Make the NL West Race Closer Than it Needed to Be?

Did the Giants' Front Office Make the NL West Race Closer Than it Needed to Be? This is the question that Neil Paine asks at Baseball-Reference.

His argument is that the Giants cost themselves wins by not bringing up Buster Posey earlier and that the at bats given to Bengie Molina have hurt the team. The Giants could have a much more comfortable lead instead of figthing for every game.

Here is his argument:

You see, while Posey was spending 47 games in Fresno, the Giants gave the majority of their starts -- and 221 plate appearances -- to Bengie Molina in his stead. While he was keeping the seat warm for Posey's eventual arrival, the since-departed Molina turned in a truly terrible performance, producing a .644 OPS (well below the NL average of .715 for catchers) and registering -5 fielding runs above avg. behind the plate. Add it up, and Molina's 221 PA gave the Giants -0.4 Wins Above Replacement (WAR).

Needless to say, after Posey assumed the starting job, San Francisco's production at catcher skyrocketed. His 134 OPS+ is second only to Joe Mauer among ML catchers, and his overall performance has been worth 2.6 WAR in just 372 PA. If you assume he would have maintained the same pace had he been starting all season long, and you give Molina's early-season PA to Posey instead, you find that playing Posey all season would have increased San Francisco's win total by 1.9 wins, which would give the Giants a far more comfortable 2½-game cushion in the West, as opposed to their current ½-game lead over the Padres. If San Diego comes back and wins by fewer than 3 games, you can point to Brian Sabean's decision to delay Posey's arbitration as a big factor in their losing the division.

It looks like in hindsight that this may have cost the team wins but things don't always turn out this way with "can't miss" prospects. Look at what happened with Matt Wieters in Baltimore. He was supposed to be the savior and his first experience in the big leagues was full of growing pains after destroying AAA like Posey had.

That being said I had some trouble just extrapolating Posey's Big league numbers backward like was done in the Baseball-Reference case but even using the actual minor league numbers and scaling them to the major league equivalent the analysis is the same. Using Posey's actual performance he could have been worth about 2.09 wins above replacement.(the math: wRAA = 10.38, Positional Adjustment = 3.626, Fielding = 0, Replacement = 6.933, total = 20.939 runs above replacement)

Those wins could come back to bight the Giants but for now with the information that was available at the time it was a borderline call and the Giants played it conservative hoping to save some future arbitration money and hope that Molina could hold his own and be somewhat valuable.

In hindsight it was probably the wrong call but when dealing in prospects it could have just as easily gone the other way. Let's just hope that those 2 wins don't kill the Giants.

Giants on the WAR Leader Boards

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Last season the Giants were unquestionably lead by their awesome pitching staff. This season the pitchers have had some company among the tops of the WAR leader boards.

The Giants have placed 2 men in the top 9 among NL batters. Andres Torres leads the way coming in tied for third with Albert Pujols at 5.8 WAR. Aubrey Huff who has been everything and more Giants fans could have hoped for this season sits at number 9 with 4.7 WAR.

The pitchers do pretty well for themselves too. Among qualified starters the Giants place 4 guys in the top 35. Leading the way for the team despite a relative down year is Tim Lincecum who checks in at number 5 with a 3.9 WAR. Not far behind at number 12 is Matt Cain with a 3.6 WAR. The other 2 full time starters, Jonathan Sanchez and Barry Zito check in a 31 and 35 respectively with WARs of 2.0 and 1.8.

Brian Wilson who has been an absolute beast for the Giants comes in at number 2 among revilers. He sports a WAR of 2.3 and is just 0.1 Wins behind leader and strike out machine Carlos Marmol.

One last piece that should come as no surprise to anyone is that Andres Torres is the National League leader in Fielding runs above replacement with a staggering 18.4! Torres has been a special player and I hope that he gets the recognition that he deserves in the end of year awards.

Here are the full lists of Giants Values this season to date: