Edgar Martinez same OPS+ as 4 other Hall of Famers but way behind in fielding innings.

Edgar Martinez was elected to Hall of Fame with three pitchers, including relief pitcher Mariano Rivera (1,283 innings). Martinez is tied with four other Hall of Fame players in OPS+ since 1903:

Rk	Player	PA	OPS+	From	To	Age	G	AB	R	H	2B	3B	HR	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos	Tm
1	Jim Thome	10313	147	1991	2012	20-41	2543	8422	1583	2328	451	26	612	1699	1747	173	2548	69	1	74	165	19	20	.276	.402	.554	.956	3D5H	CLE-PHI-CHW-LAD-MIN-BAL
2	Mike Schmidt	10062	147	1972	1989	22-39	2404	8352	1506	2234	408	59	548	1595	1507	201	1883	79	16	108	156	174	92	.267	.380	.527	.908	*53/H64	PHI
3	Willie McCovey	9692	147	1959	1980	21-42	2588	8197	1229	2211	353	46	521	1555	1345	260	1550	69	5	70	176	26	22	.270	.374	.515	.889	*3H7/9D	SFG-SDP-OAK
4	Willie Stargell	9027	147	1962	1982	22-42	2360	7927	1194	2232	423	55	475	1540	937	227	1936	78	9	75	143	17	16	.282	.360	.529	.889	*73H/98	PIT
5	Edgar Martinez	8674	147	1987	2004	24-41	2055	7213	1219	2247	514	15	309	1261	1283	113	1202	89	10	77	190	49	30	.312	.418	.515	.933	*D5/H3	SEA

POS is primary fielding position, including DH, which obviously is not a fielding position; sorted by PA:

		Total			DH		% innings
	Pos	PA	Innings	Inn/PA	PA	DH/Tot	more than Martinez
Thome	1B	10,313	13,657	1.32	3,451	33.5%	182.8%
Schmidt	3B	10,062	20,325	2.02	0	0.0%	320.9%
McCovey	1B	9,692	18,817	1.94	25	0.3%	289.7%
Stargell	OF	9,027	17,956	1.99	0	0.0%	271.8%
Martinez	DH	8,674	4,829	.56	6,218	71.7%
Rivera	P	4	1,283	320.75	0	0.0%	-73.4%

72%. That's the percent of plate appearances (PA) that Martinez had as a designated hitter. Among these five batters, only Thome had a significant percent of PA as DH.

Schmidt played 321% more innings in the field than Martinez. Playing the field takes time and effort. It exposes the player to injury. Martinez did not have those factors detracting from his batting performance nearly as much as these players who still achieved the same production in the batter's box.