If we combine both hitting and pitching, where does Babe Ruth's 1918 season rank in Championship Win Probability Added?

Here is how Baseball Reference defines it. 

"Championship Win Probability Added (cWPA): for Offensive Player Given average teams, this is the change in probability, displayed in percentage points. A change of +/- 100% would indicate one world series win added or lost."

To do well in this a player or pitcher most likely needs to be on a team that was in a close pennant race and perform well. 

The Red Sox won the pennant by just 2.5 games and Ruth performed very well in both hitting and pitching in the last 2 months (there will be details on this later to show how good Ruth was). As I will also show, adding Ruth's cWPA from both hitting and pitching will rank him very high all-time. 

All data used is from BB Ref and Stathead. 

Here are the top 10 batters in cWPA in the AL in 1918:

1	Ruth • BOS	19.70
2	Hooper • BOS	17.10
3	Bodie • NYY	5.60
4	Baker • NYY	4.90
5	Roth • CLE	4.90
6	Speaker • CLE	4.70
7	Mayer • BOS	3.90
8	Wood • CLE	3.60
9	Pipp • NYY	3.20
10	Collins • CHW	3.10

Notice the top two, by far, are from the champion Red Sox. Ruth actually had 19.67 as shown on the Single-Season Leaders & Records for Championship WPA (cWPA) for hitters.

Here are the top 10 pitchers in cWPA in the AL in 1918:

1	Jones • BOS	11.80
2	Johnson • WSH	10.20
3	Ruth • BOS	10.00
4	Coveleski • CLE	9.40
5	Bush • BOS	6.80
6	Mays • BOS	5.30
7	Bagby • CLE	4.50
8	Harper • WSH	4.40
9	Thormahlen • NYY	4.30
10	Morton • CLE	3.90

Ruth actually had 9.96 as shown on the Single-Season Leaders & Records for Championship WPA (cWPA) for Pitchers.

So Ruth has a total of 9.96 + 19.67 = 29.63. That is higher than all but 9 hitting seasons and all but 7 pitching seasons. So, overall, that would be the 17th highest season by any man whether a pitcher or hitter.

But since we are adding Ruth's hitting and pitching cWPAs together, let's add in the cWPA on offense for the pitchers. Most of them are negative. I looked at each pitcher in the top 30 of cWPA. Waite Hoyt is number 30 with 22.84. For him to reach 29.63, he would need 6.79. It is not likely a pitcher would have that much (see technical notes).

I re-calculated the cWPA of each of the top 30 pitchers by adding in their cWPAs as hitters. For most of them this meant lowering their total cWPA for the year since most of them had a negative cWPA as hitters. 

This table shows the top 15 all-time (since 1912-that is how far back BB Ref goes on this):

Rank	Player	Year	cWPA	Role
1	Carl Yastrzemski	1967	52.14	Pos. Player
2	Bobby Thomson	1951	50.19	Pos. Player
3	Willie Mays	1962	45.64	Pos. Player
4	Babe Ruth	1921	44.90	Pos. Player
5	Al Wickland	1915	38.87	Pos. Player
6	Claude Hendrix	1914	34.70	Pitcher
7	Tommy Davis	1962	34.57	Pos. Player
8	Vic Raschi	1949	34.14	Pitcher
9	Carl Hubbell	1933	32.48	Pitcher
10	Ellis Kinder	1949	31.50	Pitcher
11	Babe Ruth	1924	31.07	Pos. Player
12	Gene Bearden	1948	30.66	Pitcher
13	Jackie Robinson	1951	30.51	Pos. Player
14	Ken Keltner	1948	30.08	Pos. Player
15	Babe Ruth	1918	29.63	Both

So Ruth's 1918 season is 15th. Just on hitting it was 57th. On pitching alone it was 265th.

Now let's look at how Ruth did in the last 2 months of the 1918 season (they won the pennant by just 2.5 games). Here are all the Red Sox batters with 50+ PAs in each of the last two months of the season ranked by OPS:

Player	July OPS	July PA		Player	Aug. OPS	Aug. PA
Ruth	0.931	108		Ruth	0.782	98
Hooper	0.735	128		Strunk	0.729	117
McInnis	0.728	89		Shean	0.665	121
Strunk	0.629	104		Hooper	0.607	122
Shean	0.548	82		McInnis	0.586	112
Schang	0.472	60		Scott	0.404	105
Scott	0.421	106		Cochran	0.303	55
Stansbury	0.414	54

Ruth was clearly the best hitter on the Red Sox in each of the last two months of the season. The AL had a .644 OPS in July and .637 in Aug. The Red Sox only played 2  games in Sept. The season was only 126 games long due to World War I. They actually clinched on Aug. 31. So Ruth hit much better than the rest of the league down the stretch. 

Ruth was 3-0 with a 1.88 ERA in 24 IP in July (the league average was 2.81). In Aug. he was 6-2 with a 1.73 ERA in 73 IP (the league average was 2.74). Here is what Red Sox pitchers did in Aug.

Player	IP	W	L	ERA
Ruth	73	6	2	1.73
Mays	69	4	4	3.13
Bush	51	1	6	3.00
Jones	44	4	1	1.43
Kinney	11	0	0	2.45
Pertica	3	0	0	3.00

Although Sad Sam Jones beats Ruth in ERA Ruth had alot more IP. Ruth had a cWPA of 10.0 in Aug. and Jones had 2.1. So it is reasonable to say Ruth was the key pitcher for the Red Sox in Aug. 

Technical notes: 

I looked at all pitchers with at least an .800 OPS with 100+ PAs since 1912 (the year cWPA data starts). The highest cWPA year was 4.6 by Walter Johnson who had a 1.033 OPS in 1925. Then I looked at all the cWPA events of 2.0 or higher by pitchers thinking that maybe some one like that might have racked up a high season cWPA. But none of the 22 pitchers were as high as 4.6. So its unlikely that any pitcher ever had as high as 6.79 cWPA as a hitter.