Mickey Mantle was a great left handed hitter.

See previous post.

For cumulative seasons, From 1950 to 2013, vs RHP as LHB (within Platoon Splits), (requiring PA≥4500 and onbase_plus_slugging≥.920), sorted by greatest On-Base Plus Slugging for this split

Rk	I	Player	Split	From	To	G	OPS	GS	PA	AB	R	H	2B	3B	HR	RBI	SB	CS	BB	SO	BA	OBP	SLG	OPS	TB	GDP	HBP	SH	SF	IBB	ROE	BAbip
1		Barry Bonds	vs RHP as LHB	1986	2007	2607	1.084		8459	6496		1967	400	48	535	1336	367	93	1852	964	.303	.458	.626	1.084	4068	111	52	2	57	577	54	.283
2		Jim Thome	vs RHP as LHB	1991	2012	2317	1.034		7412	5933		1735	340	24	494	1277	16	15	1381	1703	.292	.426	.608	1.034	3605	120	43	0	55	168	45	.327
3		Todd Helton	vs RHP as LHB	1997	2013	1948	1.014		6444	5362		1762	444	27	289	981	22	24	982	695	.329	.431	.583	1.014	3127	112	30	0	67	168	58	.331
4		Lance Berkman	vs RHP as LHB	1999	2013	1698	1.008		5819	4787		1471	337	24	314	987	63	34	946	984	.307	.423	.584	1.008	2798	92	47	0	39	140	46	.328
5		Larry Walker	vs RHP as LHB	1989	2005	1765	.993		5613	4798		1515	334	42	293	885	168	48	694	839	.316	.407	.586	.993	2812	109	72	5	44	115	41	.329
6		Carlos Delgado	vs RHP as LHB	1993	2009	1874	.981		6167	5110		1466	338	10	383	1089	8	7	879	1182	.287	.399	.582	.981	2973	100	117	0	61	171	33	.300
7	I	Stan Musial	vs RHP as LHB	1950	1963	1399	.980		4590	3903		1263	252	35	203	716	14	23	640	251	.324	.418	.562	.980	2194	109	15	0	32	177	43	.305
8		David Ortiz	vs RHP as LHB	1997	2013	1682	.973		5390	4540		1329	329	11	312	957	9	7	795	938	.293	.396	.576	.973	2616	106	12	0	43	119	24	.305
9	I	Mickey Mantle	vs RHP as LHB	1951	1968	1965	.965		6573	5260		1477	205	42	369	1000	123	31	1260	1262	.281	.419	.546	.965	2873	47	10	11	32	96	60	.303
10		Duke Snider	vs RHP as LHB	1950	1964	1799	.958		6445	5556		1686	281	61	351	1078	71	61	820	895	.303	.393	.566	.958	3142	139	15	28	26	151	84	.308
11		Brian Giles	vs RHP as LHB	1995	2009	1683	.958		5616	4640		1402	315	36	245	829	92	38	891	566	.302	.414	.544	.958	2524	89	33	1	50	107	36	.298
12		Jason Giambi	vs RHP as LHB	1995	2013	1973	.954		6150	4972		1422	289	8	323	1007	13	8	1033	1015	.286	.412	.542	.954	2696	109	79	1	65	91	31	.297
13		Jim Edmonds	vs RHP as LHB	1993	2010	1809	.951		5940	5069		1499	341	22	318	920	56	39	790	1216	.296	.391	.560	.951	2838	87	31	6	44	90	33	.330
14		Chipper Jones	vs RHP as LHB	1993	2012	2298	.947		7686	6451		1956	402	26	361	1206	117	37	1144	1005	.303	.405	.541	.947	3493	164	13	2	76	143	70	.309
15		Ken Griffey	vs RHP as LHB	1989	2010	2401	.936		7816	6710		1951	375	29	444	1278	159	57	993	1133	.291	.382	.554	.936	3716	143	42	3	68	226	62	.290
16	I	Willie Stargell	vs RHP as LHB	1962	1982	2004	.935		6442	5620		1649	319	40	365	1108	14	13	726	1257	.293	.376	.559	.935	3143	108	48	2	46	200	48	.318
17		Fred McGriff	vs RHP as LHB	1986	2004	2186	.930		6989	5946		1746	333	10	367	1063	58	19	970	1210	.294	.392	.538	.930	3200	153	24	0	49	162	54	.312
18		Willie McCovey	vs RHP as LHB	1959	1980	2242	.926		7344	6157		1706	274	39	421	1189	21	14	1085	1034	.277	.387	.539	.926	3321	139	49	0	50	245	76	.270
19		Will Clark	vs RHP as LHB	1986	2000	1727	.925		5579	4760		1478	299	30	220	793	36	33	727	780	.311	.400	.525	.925	2497	62	24	9	59	143	49	.329
20	I	Eddie Mathews	vs RHP as LHB	1952	1968	2027	.925		7388	6240		1774	287	56	391	1079	58	30	1076	880	.284	.388	.536	.925	3346	94	15	12	45	135	81	.276
21		Ryan Klesko	vs RHP as LHB	1992	2007	1622	.920		5064	4329		1256	280	24	247	824	74	35	668	750	.290	.383	.537	.920	2325	100	14	1	46	82	48	.299
22		Bobby Abreu	vs RHP as LHB	1996	2012	2145	.920		7198	5987		1795	420	48	250	1022	333	108	1130	1231	.300	.409	.511	.920	3061	111	20	1	60	109	50	.338

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 4/21/2013.

In 3,250 plate appearances from 1950 through 1960 lefty batter Ted Williams against righty pitchers had OPS 1.166.  Of the batters ahead of Mantle, Musial is the only one from Mantle's era; all the others played in the recent high offense era.