Mickey Mantle: .400 BA batting only righty?

Righty against lefty pitchers:
Year  Tot vLhome vLroad   vLefties
1956 .353     .408 .338        .375
1957 .365     .417 .426        .421
1958 .304     .328 .436        .377
1961 .317     .337 .413        .371
1963 .314     .350 .435        .409 (66 AB v. lefties, 172 total AB)
1964 .303     .473 .381        .424

Four times on the road, three times at home, two times overall Mickey batted over .400 batting righty against lefty pitchers.  How rare is this?

From 1951 to 2013, vs LHP as RHB (within Platoon Splits), (requiring AB≥150 and batting_avg≥.400)

Rk	I	Player	Split	Year	G	BA	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	tOPS+	sOPS+
1		Buster Posey	vs LHP as RHB	2012	68	.433		181	164		71	18	1	13	47	0	1	14	21	.433	.470	.793	1.262	130	5	0	0	3	1	4	.436	160	229
2		Mickey Mantle	vs LHP as RHB	1964	75	.424		186	158		67	11	1	15	51	3	2	28	26	.424	.511	.791	1.302	125	5	0	0	0	5	2	.444	155	263
3		Elston Howard	vs LHP as RHB	1961	68	.423		178	163		69	7	3	8	35	0	0	12	20	.423	.466	.650	1.117	106	3	2	0	1	2	5	.449	139	199
4		Mickey Mantle	vs LHP as RHB	1957	60	.421		175	152		64	13	4	8	28	2	1	23	19	.421	.497	.717	1.214	109	1	0	0	0	6	5	.448	105	230
5		Albert Pujols	vs LHP as RHB	2008	83	.411		195	158		65	15	0	11	32	2	0	35	11	.411	.518	.715	1.233	113	4	1	0	1	14	1	.394	122	216
6		Mariano Duncan	vs LHP as RHB	1990	81	.410		202	188		77	17	4	4	27	5	3	10	22	.410	.437	.606	1.044	114	5	0	3	1	1	3	.448	154	182
7	I	Roberto Clemente	vs LHP as RHB	1964	74	.409		203	176		72	17	2	7	27	0	1	22	19	.409	.468	.648	1.115	114	5	0	2	3	12	1	.425	154	212
8		Kirby Puckett	vs LHP as RHB	1991	65	.406		165	155		63	8	5	7	24	3	2	8	19	.406	.436	.658	1.094	102	7	0	2	0	0	0	.434	167	196
9		Victor Martinez	vs LHP as RHB	2010	69	.400		167	155		62	17	0	12	39	0	0	10	14	.400	.431	.742	1.173	115	9	0	0	2	3	1	.382	173	210

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 5/16/2013.

Neither Howard nor Duncan had enough plate appearances (PA) to qualify:
- Howard: 482 PA, 446 AB
- Duncan: 471 PA, 435 AB.

Thursday, May 9, 2013
Mickey Mantle batting only righty: .323 BA; .400 twice.

Mickey in the Twilight Zone (TZ) of batting only righty ...
1957 .411
1964 .419
___________________________________

As indicated in the post above, TZ Mickey for full seasons batting right handed against all pitchers might have had batting averages (BA) over .400 in 1957 and 1964: .411 and .419.

In 1957 and 1964 Real Mickey had BA over .400 batting righty but, of course, only against lefty pitchers.  I did NOT simply assume that Mickey would have the same BA batting righty against righty pitchers.  Instead, as I have done in recent posts on Mickey Mantle, I applied to his real average, in this case BA, against righty pitchers home and righty pitchers road, the percent difference for that season for all MLB batters between:
- righty batters against lefty pitchers (the base)
- righty batters against righty pitchers.

I weighted Mickey's BA by his AB, home and road, in figuring his season BA.

Here are the MLB percent differences for each of Mantle's 18 seasons:
Year  MLB BA% Dif

1951 -6.02%
1952 -5.08%
1953 -4.81%
1954 -5.26%
1955 -3.47%
1956 -6.77%
1957 -4.58%
1958 -5.32%
1959 -2.71%
1960 -6.42%
1961 -6.72%
1962 -6.06%
1963 -7.48%
1964 -5.43%
1965 -5.98%
1966 -3.17%
1967 -5.98%
1968 -7.35%
ave. -5.48%

In 1957 TZ Mickey got a break in that the MLB percent difference was below the overall -5.48%, it was only -4.58%.  So TZ Mickey's "penalty" was less than the general average during his career.  In 1964 it was about even: -5.43%, essentially no "penalty".

Now you could be completely anal about this and simply blow it off as idle conjecture or you can think about whether Mickey Mantle could have been the only .400 hitter since Ted Williams batted .406 in 1941 had Mickey's father not forced Mickey to switch hit.