most ip by a pitcher in a season with less than 0.50 era

Buck O'Brien has pitched the most innings with an ERA better than 0.50 in a season, with 47.2 innings in his rookie season in 1911.

	NAME	IP	ERA	SEASON	TM	G	W	L	W%	GS	SO	CG	SHO	SV	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	ERA-	FIP	FIP-	H/9	PRAA
1	Buck O'Brien B. O'Brien	47.2	0.38	1911	BSA	6	5	1	.833	5	31	5	2	0	30	2	9	0	21	1	1		189	0	5.85	3.97	1.48	0.00	16.4	11.1	1.07	.221	1.70	11	2.85	88	5.66	2
2	Kevin Siegrist K. Siegrist	39.2	0.45	2013	STL	45	3	1	.750	0	50	0	0	0	17	2	2	1	18	1	15	1	152	0	11.34	4.08	2.78	0.23	32.9	11.8	0.88	.195	0.45	12	2.29	61	3.86	6.4
3	Devin Williams D. Williams	27.0	0.33	2020	MIL	22	4	1	.800	0	53	0	0	0	8	1	4	1	9	1	1	0	100	3	17.67	3.00	5.89	0.33	53.0	9.0	0.63	.194	1.33	7	0.85	19	2.67	10.8
4	Earl Moore E. Moore	26.0	0.00	1908	PHN	3	2	1	.667	3	16	3	1	0	20	0	4	0	8	2	0		102	1	5.54	2.77	2.00	0.00	15.7	7.8	1.08	.263	1.38	0	2.02	83	6.92	1.2
5	J.P. Feyereisen	24.1	0.00	2022	TBR	22	4	0	1.000	2	25	0	0	1	7	0	1	0	5	0	3	0	86	0	9.25	1.85	5.00	0.00	29.1	5.8	0.49	.125	0.37	0	1.67	44	2.59	5.9
6	Joba Chamberlain J. Chamberlain	24.0	0.38	2007	NYY	19	2	0	1.000	0	34	0	0	1	12	1	2	1	6	1	3	0	91	1	12.75	2.25	5.67	0.38	37.4	6.6	0.75	.224	0.75	8	1.81	41	4.50	7
7	Cliff Markle C. Markle	23.0	0.39	1915	NYY	3	2	0	1.000	2	12	2	0	0	15	1	3	1	6	0	1		87	1	4.70	2.35	2.00	0.39	13.8	6.9	0.91	.206	1.17	13	2.71	91	5.87	0.7
8	Joel Johnston J. Johnston	22.1	0.40	1991	KCR	13	1	0	1.000	0	21	0	0	0	9	1	1	0	9	0	1	3	85	0	8.46	3.63	2.33	0.00	24.7	10.6	0.81	.164	0.40	10	2.18	56	3.63	4.4
9	Jake Diekman J. Diekman	21.1	0.42	2020	OAK	21	2	0	1.000	0	31	0	0	0	8	1	2	1	12	1	2	1	84	0	13.08	5.06	2.58	0.42	36.9	14.3	0.94	.179	0.84	10	2.71	63	3.38	3.9
10	Craig Kimbrel C. Kimbrel	20.2	0.44	2010	ATL	21	4	0	1.000	0	40	0	0	1	9	1	2	0	16	0	7	1	88	4	17.42	6.97	2.50	0.00	45.5	18.2	1.21	.281	0.87	11	1.52	39	3.92	5.6
11	Tyler Olson T. Olson	20.0	0.00	2017	CLE	30	1	0	1.000	0	18	0	0	1	13	0	0	0	6	1	4	0	77	0	8.10	2.70	3.00	0.00	23.4	7.8	0.95	.250	0.00	0	2.40	55	5.85	4.4
12	Harry Coveleski H. Coveleski	20.0	0.00	1907	PHN	4	1	0	1.000	0	6	0	0	0	10	0	2	0	3	1	4		72	0	2.70	1.35	2.00	0.00	8.3	4.2	0.65	.161	0.90	0	2.18	83	4.50	1
13	Arlie Pond A. Pond	20.0	0.45	1898	BAL	3	1	1	.500	2	4	1	1	0	8	1	4	0	9	2	1		76	1	1.80	4.05	0.44	0.00	5.3	11.8	0.85	.131	1.80	12	4.02	111	3.60	-0.9
14	Danny Coulombe D. Coulombe	18.1	0.49	2025	MIN	22	1	0	1.000	0	21	0	0	2	10	1	1	0	3	0	7	0	68	0	10.31	1.47	7.00	0.00	30.9	4.4	0.71	.227	0.49	12	1.27	31	4.91	5.7
15	Chris Flexen C. Flexen	18.1	0.00	2025	CHC	11	4	0	1.000	0	10	0	0	1	10	0	1	0	5	0	9	0	67	1	4.91	2.45	2.00	0.00	14.9	7.5	0.82	.192	0.49	0	2.79	72	4.91	2.3
16	Drew Pomeranz D. Pomeranz	18.1	0.00	2025	CHC	20	2	1	.667	2	16	0	0	1	7	0	1	0	5	3	5	0	66	0	7.85	2.45	3.20	0.00	24.2	7.6	0.65	.167	0.49	0	2.63	68	3.44	2.6
17	Jarlín García J. García	18.1	0.49	2020	SFG	19	2	1	.667	0	14	0	0	0	11	1	6	0	7	2	5	1	73	0	6.87	3.44	2.00	0.00	19.2	9.6	0.98	.220	2.95	11	3.13	73	5.40	2.4
18	Brent Suter B. Suter	18.1	0.49	2019	MIL	9	4	0	1.000	0	15	0	0	0	10	1	1	1	1	0	0	0	65	0	7.36	0.49	15.00	0.49	23.1	1.5	0.60	.188	0.49	11	2.44	55	4.91	4
19	Donnie Hart D. Hart	18.1	0.49	2016	BAL	22	0	0		0	12	0	0	0	12	1	1	1	6	0	3	1	71	0	5.89	2.95	2.00	0.49	16.9	8.5	0.98	.212	0.49	12	3.52	81	5.89	1.7
20	Tony Faeth T. Faeth	18.1	0.49	1919	CLE	6	0	0		0	7	0	0	0	13	1	4	0	10	0	4		68	0	3.44	4.91	0.70	0.00	10.3	14.7	1.25	.255	1.96	15	3.36	103	6.38	-0.1
21	Karl Spooner K. Spooner	18.0	0.00	1954	BKN	2	2	0	1.000	2	27	2	2	0	7	0	0	0	6	0	0		68	0	13.50	3.00	4.50	0.00	39.7	8.8	0.72	.200	0.00	0	0.40	10	3.50	7.3
22	Fernando Valenzuela F. Valenzuela	17.2	0.00	1980	LAD	10	2	0	1.000	0	16	0	0	1	8	0	2	0	5	0	4	0	66	0	8.15	2.55	3.20	0.00	24.2	7.6	0.74	.178	1.02	0	1.78	49	4.08	3.6
23	Brad Wieck B. Wieck	17.0	0.00	2021	CHC	15	0	0		0	28	0	0	0	10	0	0	0	10	0	5	0	71	0	14.82	5.29	2.80	0.00	39.4	14.1	1.18	.303	0.00	0	1.63	39	5.29	4.9
24	Mike Norris M. Norris	16.2	0.00	1975	OAK	4	1	0	1.000	3	5	1	1	0	6	0	2	0	8	0	0	0	65	0	2.70	4.32	0.63	0.00	7.7	12.3	0.84	.115	1.08	0	3.42	89	3.24	0.8
25	Wayne Twitchell W. Twitchell	16.0	0.00	1971	PHI	6	1	0	1.000	1	15	0	0	0	8	0	4	1	10	1	2	0	69	0	8.44	5.63	1.50	0.56	21.7	14.5	1.13	.167	2.25	0	3.45	99	4.50	0.1