Is Slugging Percentage Twice As Important For Pitchers With Runners On Base?

While looking into something else, I did the following regressions: ERA was the dependent variable while opponents' OBP & SLG, each with no runners on (NONE) and runners on base (ROB) were the independent variables. The data set included all pitcher seasons of 140+ IP from 2007-2013. There were 740 pitchers. Here is the equation

ERA = 3.21*NONESLG +  7.06*NONEOBP + 6.30*ROBSLG + 7.06*ROBOBP  -4.40

The r-squared was .866 and the standard error was .30. The t-values for the independent variables were all at least 10. So it seems, at least on the surface, that SLG has twice the impact on ERA when there are runners on base as when there are no runners on. Maybe if a pitcher's ERA seems high for his underlying stats it could be he has a high OBP with runners on base.

Trout Might Be Second Greatest Young Hitter Ever

The table below shows the OPS+ leaders up through age 22 for guys with 1000+ PAs.

Rk	Player	OPS+	PA	From	To
1	Ted Williams	182	1942	1939	1941
2	Mike Trout	169	1813	2011	2014
3	Stan Musial	166	1285	1941	1943
4	Ty Cobb	163	2486	1905	1909
5	Jimmie Foxx	159	1976	1925	1930
6	Albert Pujols	154	1351	2001	2002
7	Eddie Mathews	153	1874	1952	1954
8	Rogers Hornsby	150	1665	1915	1918
9	Tris Speaker	150	1359	1907	1910
10	Eddie Collins	150	1066	1906	1909
11	Mickey Mantle	148	2201	1951	1954
12	Joe DiMaggio	147	1361	1936	1937
13	Mel Ott	147	2644	1926	1931

If we go up to age 23, Trout is 4th (or tied for 5th, Musial also gets 169). Williams has 190, Pete Browning has 188 and Cobb has 171. But Browning still only had 1137 PAs.

I estimate that even if Trout has an OPS+ of just 60 the rest of this season, he would still be at 149 or in the top 10. If he can do 158 the rest of the way, he will still be at 167 (he is at 183 so far this year). So he would still be in 2nd place. This is extremely outstanding company that he is in.

For wRC+ that is listed at Fangraphs, he still does very well on the list up through age 22.Fangraphs has Jackson being born in 1889 while Baseball Reference has 1887

Joe Jackson	181
Ted Williams	177
Stan Musial	170
Mike Trout	166
Jimmie Foxx	160
Ty Cobb	159
Albert Pujols	154
Eddie Collins	151
Eddie Mathews	150
Mickey Mantle	149
Tris Speaker	149
Mel Ott	147
Rogers Hornsby	146
Joe DiMaggio	144

How Good Was Sandy Koufax Outside of Dodger Stadium?

I originally posted this to Beyond the Box Score in 2006.

Probably every baseball fan knows who Sandy Koufax was and that he was a great pitcher back in the 1960s. Some evidence shows that he was great. Here are the best ten ERAs in all of baseball from 1962-1966 (the years Koufax pitched in Dodger Stadium) for pitchers with 810 or more innings pitched:

1    Sandy Koufax               1.95  

2    Juan Marichal              2.50  

3    Gary Peters                2.58  

4    Whitey Ford                2.74  

5    Don Drysdale               2.75  

6    Bob Veale                  2.75  

7    Dean Chance                2.77  

8    Jim Maloney                2.79  

9    Joe Horlen                 2.83  

10   Bob Gibson                 2.95 

(the 810 IP works out to 162 per season). Pretty impressive lead for Koufax. But Dodger Stadium favored the pitchers. Here are its park factors for the 1962-66 seasons from the STATS, INC. All-Time Baseball Sourcebook:

Year	Run Factor	HR Factor
1962	82(1)	50(1)
1963	84(1T)	63(2)
1964	78(1)	62(1)
1965	76(1)	49(1)
1966	86(1)	70(2)

The 82 for the run factor in 1962 means that the number of runs scored in Dodger Stadium was only 82% of the National League average. The number in parentheses indicates Dodger Stadium’s rank in how much it favored the pitchers. That is, the 82 for run factor in 1962 was the lowest in the league. The 84 in 1963 was tied. It is pretty clear that Koufax pitched in a great park for pitchers. To adjust for park factors, the table below shows the NL leaders in RSAA from 1962-66.  RSAA comes from the Lee Sinins' Complete Baseball Encyclopedia. Here is the definition: "RSAA--Runs saved against average. It's the amount of runs that a pitcher saved vs. what an average pitcher would have allowed." It is also park adjusted, so that pitchers who pitch in good hitter's parks get an adjustment upward in their RSAA, and vice-versa. A below average pitcher will have a negative RSAA.

1    Sandy Koufax                194  

2    Juan Marichal               172  

3    Bob Gibson                  131  

4    Jim Maloney                 114  

5    Jim Bunning                  92  

6    Don Drysdale                 84  

7    Bob Veale                    82  

8    Larry Jackson                68  

9    Chris Short                  64  

10   Bob Friend                   55  

Koufax has a pretty big edge over the number two man, Marichal, even with the park factors taken into account (the factors used in the Lee Sinins' Complete Baseball Encyclopedia are not necessarily the same as those in the STATS, INC. All-Time Baseball Sourcebook). Of course, this period covers Koufax’s prime and may not cover the exact prime years of anyone else. This was definitely not the best five-year performance any pitcher ever had (see my article below called “The Best Five-Year Pitching Performances”). http://cybermetric.blogspot.com/2014/06/the-best-five-year-pitching-performances.html

Adjusting for park factors does not always tell the whole story. Some pitchers benefit disproportionately from their parks. Koufax had a 1.37 ERA in home games over this period while it was 2.57 in road games (data from Retrosheet). The home/road ratio was .533. That means that he allowed only about 53.3% as many runs at home as he did on the road. Looking at Table 2, we can see that the normal rate was about 80% for Dodger Stadium. So yes, Koufax did benefit alot more than normal from his park. Koufax also allowed 55 HRs in road games while facing 2,681 batters for a rate of 2.05%. At home, it was 34/2,714 for a rate of 1.25%. Since 1.25/2.05 is about .61, it means his HR rate at home was 61% of what it was on the road. The average HR factor for Dodger Stadium from 1962-66, weighted by Koufax’s IP in each season, was 59.35, just a little under 61. So Koufax, when it comes to HRs, benefited from Dodger Stadium, but just a little less than average. He had a 5.31 strikeout-to-walk ratio at home and 3.97 on the road.

Over the 1962-66 period, the average ERA in home games was 3.40 and 3.76 on the road for all NL pitchers. So the home/road ratio was .904. That far exceeds Koufax’s .533. Koufax’s differential of 1.20 was far higher than the normal differential of .36. Another way to look at this is to look at the ERA at Dodger Stadium vs. the ERA compiled in Dodger road games. All pitchers (minus Koufax), both Dodgers and their opponents, had an ERA of 3.10 in games at Dodger Stadium. In road games, it was 3.69. So the ratio is .84 (3.10/3.69). Again, that is far higher than for Koufax. The differential of .59 is only half of what it was for Koufax.

I also compared Koufax to some of the other good NL pitchers from this time by using their stats in neutral parks. For example, I looked at how Koufax and Juan Marichal did outside of both Dodger Stadium and Candlestick Park where the Giants played. The table below shows how Koufax compares to Marichal, Bob Gibson and Jim Bunning (only over the years 1964-66 since those were the only years Bunning was in the NL while Koufax pitched in Dodger Stadium).

Pitcher	ERA	SO/BB	HR%	IP
Koufax	2.47	4.24	2.00	576.667
Marichal	2.46	3.86	2.49	608.667
Pitcher	ERA	SO/BB	HR%	IP
Koufax	2.56	3.94	2.00	580.667
Gibson	2.48	2.32	1.52	628.667
Pitcher	ERA	SO/BB	HR%	IP
Koufax	2.56	4.02	2.19	361.667
Bunning	2.43	4.73	1.58	385.667

These other three pitchers put up numbers comparable to Koufax while pitching in neutral parks. But I don’t think it is clear how this should change our ranking or perception of Koufax. These other guys were good, if not great pitchers, too. And this analysis, of course, looks at less than half of Koufax’s IP in this period. On the other hand, it suggests that Koufax was not as far above his competition as we normally think.