Best rookie Home Run hitter: Pete Alonso or Aaron Judge? Maybe Mark McGwire? Frank Robinson, Wally Berger, ...?

Those five batters held the rookie Home Run record progressive going back to 1930.

Aaron Judge was the first rookie to reach 50 Home Runs: 52 in 2017. But then Pete Alonso hit 53 in 2019. So Alonso is the answer, right? Well, yes, if all you do is what pretty much all baseball fans do when considering Home Runs: stare at the totals.

What about the number of plate appearances (PA: AB + BB + HBP + SF + SH) or at bats (AB)? AB:

Judge 542
Alonso 597

Alonso took 55 more AB to hit only one more Home Run, so it must be Aaron Judge between those two, right? But they played in different leagues in different years. So we should look at Home Run hitting in each league in those years, right?

That's basically the flow of my logic. See my next post:

Should Sacrifice Flies (SF) be in the Home Run rate: (AB+SF)/HR? Saturday, December 18, 2021

Oh, in 1937 Detroit rookie Rudy York hit 35 Home Runs in only 375 AB! So, let's extend our evaluation beyond the six progressive record holders. Let's look at rookie seasons with at least 30 Home Runs. That list contains 32 rookies: AL 21, NL 11. Boston Brave rookie Wally Berger was the first with 38 in 1930.

This post will look at the Home Run rate: AB/HR. Lower is better. The objective is to see the percent difference between the AB/HR for the player and his league that season: Dif/(L AB/HR).

Ballpark factor for Home Run hitting should be factored in but it's beyond the scope of this post. As suggested in this blog years ago, there should be a HR+ that takes all this into account, instead of just staring at totals, which we hardly do anymore with anything else.

Below the list of 32 is sorted twice. First by Home Runs descending, year ascending. Then by percent difference from the league Home Run rate. Bold is max. Red is min.

Rk	Player	Year	HR	AB	AB/HR	L AB/HR	Dif	% Dif	OPS+	Age	Tm	Lg	G	PA	R	H	2B	3B	RBI	BB	IBB	SO	BA	OBP	SLG	Player
1	Pete Alonso	2019	53	597	11.26	25.20	13.93	55.29%	147	24	NYM	NL	161	693	103	155	30	2	120	72	6	183	.260	.358	.583	Pete Alonso
2	Aaron Judge	2017	52	542	10.42	26.19	15.77	60.21%	171	25	NYY	AL	155	678	128	154	24	3	114	127	11	208	.284	.422	.627	Aaron Judge
3	Mark McGwire	1987	49	557	11.37	29.54	18.18	61.52%	164	23	OAK	AL	151	641	97	161	28	4	118	71	8	131	.289	.370	.618	Mark McGwire
4	Cody Bellinger	2017	39	480	12.31	28.12	15.81	56.23%	143	21	LAD	NL	132	548	87	128	26	4	97	64	13	146	.267	.352	.581	Cody Bellinger
6	Wally Berger	1930	38	555	14.61	48.98	34.38	70.18%	137	24	BSN	NL	151	628	98	172	27	14	119	54	7	69	.310	.375	.614	Wally Berger
5	Frank Robinson	1956	38	572	15.05	34.33	19.28	56.15%	143	20	CIN	NL	152	668	122	166	27	6	83	64	7	95	.290	.379	.558	Frank Robinson
8	Al Rosen	1950	37	554	14.97	43.58	28.61	65.65%	145	26	CLE	AL	155	668	100	159	23	4	116	100	3	72	.287	.405	.543	Al Rosen
7	Albert Pujols	2001	37	590	15.95	29.84	13.90	46.57%	157	21	STL	NL	161	676	112	194	47	4	130	69	6	93	.329	.403	.610	Albert Pujols
9	José Abreu	2014	36	556	15.44	38.47	23.02	59.85%	173	27	CHW	AL	145	622	80	176	35	2	107	51	15	131	.317	.383	.581	José Abreu
13	Hal Trosky	1934	35	625	17.86	62.40	44.54	71.38%	150	21	CLE	AL	154	685	117	206	45	9	142	58	12	49	.330	.388	.598	Hal Trosky
12	Rudy York	1937	35	375	10.71	53.73	43.01	80.06%	151	23	DET	AL	104	417	72	115	18	3	101	41	3	52	.307	.375	.651	Rudy York
11	Ron Kittle	1983	35	520	14.86	40.89	26.04	63.67%	118	25	CHW	AL	145	570	75	132	19	3	100	39	8	150	.254	.314	.504	Ron Kittle
10	Mike Piazza	1993	35	547	15.63	39.62	23.99	60.55%	153	24	LAD	NL	149	602	81	174	24	2	112	46	6	86	.318	.370	.561	Mike Piazza
15	Walt Dropo	1950	34	559	16.44	43.58	27.14	62.28%	134	27	BOS	AL	136	609	101	180	28	8	144	45	3	75	.322	.378	.583	Walt Dropo
14	Ryan Braun	2007	34	451	13.26	33.08	19.82	59.90%	154	23	MIL	NL	113	492	91	146	26	6	97	29	1	112	.324	.370	.634	Ryan Braun
19	Jimmie Hall	1963	33	497	15.06	36.94	21.88	59.23%	136	25	MIN	AL	156	571	88	129	21	5	80	63	4	101	.260	.342	.521	Jimmie Hall
18	Earl Williams	1971	33	497	15.06	47.79	32.73	68.49%	123	22	ATL	NL	145	550	64	129	14	1	87	42	5	80	.260	.324	.491	Earl Williams
17	Jose Canseco	1986	33	600	18.18	33.79	15.61	46.19%	116	21	OAK	AL	157	682	85	144	29	1	117	65	1	175	.240	.318	.457	Jose Canseco
16	Ryan Mountcastle	2021	33	534	16.18	26.59	10.41	39.14%	112	24	BAL	AL	144	586	77	136	23	1	89	41	2	161	.255	.309	.487	Ryan Mountcastle
22	Tony Oliva	1964	32	672	21.00	35.58	14.58	40.97%	150	25	MIN	AL	161	719	109	217	43	9	94	34	8	68	.323	.359	.557	Tony Oliva
21	Matt Nokes	1987	32	461	14.41	29.54	15.14	51.24%	133	23	DET	AL	135	508	69	133	14	2	87	35	2	70	.289	.345	.536	Matt Nokes
20	Chris Young	2007	32	569	17.78	33.08	15.30	46.25%	88	23	ARI	NL	148	624	85	135	29	3	68	43	1	141	.237	.295	.467	Chris Young
27	Ted Williams	1939	31	565	18.23	53.51	35.28	65.94%	160	20	BOS	AL	149	677	131	185	44	11	145	107	12	64	.327	.436	.609	Ted Williams
26	Jim Ray Hart	1964	31	566	18.26	45.65	27.39	60.01%	132	22	SFG	NL	153	625	71	162	15	6	81	47	4	94	.286	.342	.498	Jim Ray Hart
25	Tim Salmon	1993	31	515	16.61	37.37	20.76	55.55%	143	24	CAL	AL	142	610	93	146	35	1	95	82	5	135	.283	.382	.536	Tim Salmon
24	Eloy Jimenez	2019	31	468	15.10	24.02	8.93	37.16%	116	22	CHW	AL	122	504	69	125	18	2	79	30	0	134	.267	.315	.513	Eloy Jimenez
23	Adolis García	2021	31	581	18.74	26.59	7.85	29.51%	101	28	TEX	AL	149	622	77	141	26	2	90	32	0	194	.243	.286	.454	Adolis García
32	Bob Allison	1959	30	570	19.00	38.46	19.46	50.60%	122	24	WSH	AL	150	639	83	149	18	9	85	60	1	92	.261	.333	.482	Bob Allison
31	Willie Montanez	1971	30	599	19.97	47.79	27.82	58.22%	124	23	PHI	NL	158	683	78	153	27	6	99	67	14	105	.255	.327	.471	Willie Montanez
30	Pete Incaviglia	1986	30	540	18.00	33.79	15.79	46.73%	109	22	TEX	AL	153	606	82	135	21	2	88	55	2	185	.250	.320	.463	Pete Incaviglia
29	Nomar Garciaparra	1997	30	684	22.80	31.58	8.78	27.81%	123	23	BOS	AL	153	734	122	209	44	11	98	35	2	92	.306	.342	.534	Nomar Garciaparra
28	Mike Trout	2012	30	559	18.63	30.97	12.34	39.84%	168	20	LAA	AL	139	639	129	182	27	8	83	67	4	139	.326	.399	.564	Mike Trout
Rk	Player	Year	HR	AB	AB/HR	L AB/HR	Dif	% Dif	OPS+	Age	Tm	Lg	G	PA	R	H	2B	3B	RBI	BB	IBB	SO	BA	OBP	SLG	Player

Sorted by % Dif:

Rk	Player	Year	HR	AB	AB/HR	L AB/HR	Dif	% Dif	OPS+	Age	Tm	Lg	G	PA	R	H	2B	3B	RBI	BB	IBB	SO	BA	OBP	SLG	Player
12	Rudy York	1937	35	375	10.71	53.73	43.01	80.06%	151	23	DET	AL	104	417	72	115	18	3	101	41	3	52	.307	.375	.651	Rudy York
13	Hal Trosky	1934	35	625	17.86	62.40	44.54	71.38%	150	21	CLE	AL	154	685	117	206	45	9	142	58	12	49	.330	.388	.598	Hal Trosky
6	Wally Berger	1930	38	555	14.61	48.98	34.38	70.18%	137	24	BSN	NL	151	628	98	172	27	14	119	54	7	69	.310	.375	.614	Wally Berger
18	Earl Williams	1971	33	497	15.06	47.79	32.73	68.49%	123	22	ATL	NL	145	550	64	129	14	1	87	42	5	80	.260	.324	.491	Earl Williams
27	Ted Williams	1939	31	565	18.23	53.51	35.28	65.94%	160	20	BOS	AL	149	677	131	185	44	11	145	107	12	64	.327	.436	.609	Ted Williams
8	Al Rosen	1950	37	554	14.97	43.58	28.61	65.65%	145	26	CLE	AL	155	668	100	159	23	4	116	100	3	72	.287	.405	.543	Al Rosen
11	Ron Kittle	1983	35	520	14.86	40.89	26.04	63.67%	118	25	CHW	AL	145	570	75	132	19	3	100	39	8	150	.254	.314	.504	Ron Kittle
15	Walt Dropo	1950	34	559	16.44	43.58	27.14	62.28%	134	27	BOS	AL	136	609	101	180	28	8	144	45	3	75	.322	.378	.583	Walt Dropo
3	Mark McGwire	1987	49	557	11.37	29.54	18.18	61.52%	164	23	OAK	AL	151	641	97	161	28	4	118	71	8	131	.289	.370	.618	Mark McGwire
10	Mike Piazza	1993	35	547	15.63	39.62	23.99	60.55%	153	24	LAD	NL	149	602	81	174	24	2	112	46	6	86	.318	.370	.561	Mike Piazza
2	Aaron Judge	2017	52	542	10.42	26.19	15.77	60.21%	171	25	NYY	AL	155	678	128	154	24	3	114	127	11	208	.284	.422	.627	Aaron Judge
26	Jim Ray Hart	1964	31	566	18.26	45.65	27.39	60.01%	132	22	SFG	NL	153	625	71	162	15	6	81	47	4	94	.286	.342	.498	Jim Ray Hart
14	Ryan Braun	2007	34	451	13.26	33.08	19.82	59.90%	154	23	MIL	NL	113	492	91	146	26	6	97	29	1	112	.324	.370	.634	Ryan Braun
9	José Abreu	2014	36	556	15.44	38.47	23.02	59.85%	173	27	CHW	AL	145	622	80	176	35	2	107	51	15	131	.317	.383	.581	José Abreu
19	Jimmie Hall	1963	33	497	15.06	36.94	21.88	59.23%	136	25	MIN	AL	156	571	88	129	21	5	80	63	4	101	.260	.342	.521	Jimmie Hall
31	Willie Montanez	1971	30	599	19.97	47.79	27.82	58.22%	124	23	PHI	NL	158	683	78	153	27	6	99	67	14	105	.255	.327	.471	Willie Montanez
4	Cody Bellinger	2017	39	480	12.31	28.12	15.81	56.23%	143	21	LAD	NL	132	548	87	128	26	4	97	64	13	146	.267	.352	.581	Cody Bellinger
5	Frank Robinson	1956	38	572	15.05	34.33	19.28	56.15%	143	20	CIN	NL	152	668	122	166	27	6	83	64	7	95	.290	.379	.558	Frank Robinson
25	Tim Salmon	1993	31	515	16.61	37.37	20.76	55.55%	143	24	CAL	AL	142	610	93	146	35	1	95	82	5	135	.283	.382	.536	Tim Salmon
1	Pete Alonso	2019	53	597	11.26	25.20	13.93	55.29%	147	24	NYM	NL	161	693	103	155	30	2	120	72	6	183	.260	.358	.583	Pete Alonso
21	Matt Nokes	1987	32	461	14.41	29.54	15.14	51.24%	133	23	DET	AL	135	508	69	133	14	2	87	35	2	70	.289	.345	.536	Matt Nokes
32	Bob Allison	1959	30	570	19.00	38.46	19.46	50.60%	122	24	WSH	AL	150	639	83	149	18	9	85	60	1	92	.261	.333	.482	Bob Allison
30	Pete Incaviglia	1986	30	540	18.00	33.79	15.79	46.73%	109	22	TEX	AL	153	606	82	135	21	2	88	55	2	185	.250	.320	.463	Pete Incaviglia
7	Albert Pujols	2001	37	590	15.95	29.84	13.90	46.57%	157	21	STL	NL	161	676	112	194	47	4	130	69	6	93	.329	.403	.610	Albert Pujols
20	Chris Young	2007	32	569	17.78	33.08	15.30	46.25%	88	23	ARI	NL	148	624	85	135	29	3	68	43	1	141	.237	.295	.467	Chris Young
17	Jose Canseco	1986	33	600	18.18	33.79	15.61	46.19%	116	21	OAK	AL	157	682	85	144	29	1	117	65	1	175	.240	.318	.457	Jose Canseco
22	Tony Oliva	1964	32	672	21.00	35.58	14.58	40.97%	150	25	MIN	AL	161	719	109	217	43	9	94	34	8	68	.323	.359	.557	Tony Oliva
28	Mike Trout	2012	30	559	18.63	30.97	12.34	39.84%	168	20	LAA	AL	139	639	129	182	27	8	83	67	4	139	.326	.399	.564	Mike Trout
16	Ryan Mountcastle	2021	33	534	16.18	26.59	10.41	39.14%	112	24	BAL	AL	144	586	77	136	23	1	89	41	2	161	.255	.309	.487	Ryan Mountcastle
24	Eloy Jimenez	2019	31	468	15.10	24.02	8.93	37.16%	116	22	CHW	AL	122	504	69	125	18	2	79	30	0	134	.267	.315	.513	Eloy Jimenez
23	Adolis García	2021	31	581	18.74	26.59	7.85	29.51%	101	28	TEX	AL	149	622	77	141	26	2	90	32	0	194	.243	.286	.454	Adolis García
29	Nomar Garciaparra	1997	30	684	22.80	31.58	8.78	27.81%	123	23	BOS	AL	153	734	122	209	44	11	98	35	2	92	.306	.342	.534	Nomar Garciaparra
Rk	Player	Year	HR	AB	AB/HR	L AB/HR	Dif	% Dif	OPS+	Age	Tm	Lg	G	PA	R	H	2B	3B	RBI	BB	IBB	SO	BA	OBP	SLG	Player

The leaders in number of rookie Home Runs drop down significantly in rank except for one who moves up:
Alonso 20
Judge 11
McGwire 9
Berger 3
Frank Robinson 18

Rudy York

Positions: First Baseman and Catcher

Bats: Right  •  Throws: Right

6-1, 209lb (185cm, 94kg)

Born: August 17, 1913 in Ragland, AL us

Died: February 5, 1970 (Aged 56-172d) in Rome, GA

Rudy York is our champ with 35 Home Runs in 1937 in only 375 AB. He hit 34 in in 1943 for the only time he led the league but that was in the middle of World War II. He also hit 33 in both 1938 and 1940. He played in seven games in each of three World Series: 1940 (one homer) and 1945 with Detroit and 1946 with the Boston Red Sox (two homers). Here are the 1937 Home Run leaders:

Home Runs

1.	DiMaggio • NYY	46
2.	Greenberg • DET	40
3.	Gehrig • NYY	37
4.	Foxx • BOS	36
5.	York • DET	35
6.	Trosky • CLE	32
7.	Clift • SLB	29
	Dickey • NYY	29
9.	Johnson • PHA	25
	Moses • PHA	25

AB per HR

1.	York • DET	10.7
2.	DiMaggio • NYY	13.5
3.	Greenberg • DET	14.9
4.	Gehrig • NYY	15.4
5.	Foxx • BOS	15.8
6.	Dickey • NYY	18.3
7.	Trosky • CLE	18.8
8.	Johnson • PHA	19.1
9.	Clift • SLB	19.7
10.	Bonura • CHW	23.5

Joe DiMaggio was in his second season in 1937. His Home Run rate was 75% above the AL rate.

Source: https://stathead.com/ by way of https://www.baseball-reference.com/