Dave Kingman: most homers in final season: 35; most final three: 100.

Dave Kingman, Chicago Cub
September 7, 1979
by Wahkeenah from Wikimedia Commons

Dave Kingman's home runs (HR) in his final three seasons, his three with Oakland, and OPS+:
1984 35  133
1985 30  104
1986 35  90
Total: 100

Kingman is probably the only player to hit 100 home runs in his final three seasons.  His diminishing OPS+ accounts for why he was not valued for his home runs.  Or they simply looked at his low batting average and high strike outs.

Kingman had his best season with the Chicago Cubs in 1979: OPS+ 146; led National League with 48 HR, .613 SLG, .956 OPS, ... 131 SO.  Kingman also led NL in HR in 1982 with the Mets: 37 ... and 156 SO.

Here are the only players with at least 20 HR in their final season.

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Dave Kingman	35	1986	37	OAK	AL	144	604	561	70	118	19	0	94	33	3	126	3	0	7	16	3	3	.210	.255	.431	.686	*D/3H
2	Mark McGwire	29	2001	37	STL	NL	97	364	299	48	56	4	0	64	56	3	118	3	0	6	7	0	0	.187	.316	.492	.808	*3/H
3	Ted Williams	29	1960	41	BOS	AL	113	390	310	56	98	15	0	72	75	7	41	3	0	2	7	1	1	.316	.451	.645	1.096	*7H
4	Barry Bonds	28	2007	42	SFG	NL	126	477	340	75	94	14	0	66	132	43	54	3	0	2	13	5	0	.276	.480	.565	1.045	*7H/D
5	Jermaine Dye	27	2009	35	CHW	AL	141	574	503	78	126	19	1	81	64	2	108	5	0	2	15	0	2	.250	.340	.453	.793	*9/DH
6	Hank Greenberg	25	1947	36	PIT	NL	125	510	402	71	100	13	2	74	104		73	4	0		16	0		.249	.408	.478	.885	*3/H
7	Jack Graham	24	1949	32	SLB	AL	137	573	500	71	119	22	1	79	61		62	4	8		12	0	1	.238	.326	.430	.756	*3/H
8	Roy Cullenbine	24	1947	33	DET	AL	142	607	464	82	104	18	1	78	137		51	0	6		10	3	2	.224	.401	.422	.823	*3/H
9	Kendrys Morales	23	2013	30	SEA	AL	156	657	602	64	167	34	0	80	49	6	114	5	0	1	21	0	0	.277	.336	.449	.785	*D3/H
10	Albert Belle	23	2000	33	BAL	AL	141	622	559	71	157	37	1	103	52	11	68	4	0	7	17	0	5	.281	.342	.474	.817	*9D
11	Kirby Puckett	23	1995	35	MIN	AL	137	602	538	83	169	39	0	99	56	18	89	3	0	5	15	3	2	.314	.379	.515	.894	*9D/8H645
12	Phil Nevin	22	2006	35	TOT	ML	129	450	397	54	95	13	0	68	48	1	106	2	1	2	13	0	0	.239	.323	.438	.761	D3H/792
13	Sammy Sosa	21	2007	38	TEX	AL	114	454	412	53	104	24	1	92	34	3	112	3	0	5	11	0	0	.252	.311	.468	.779	*D9H
14	Paul O'Neill	21	2001	38	NYY	AL	137	563	510	77	136	33	1	70	48	4	59	2	0	3	20	22	3	.267	.330	.459	.789	*9/DH
15	Will Clark	21	2000	36	TOT	ML	130	507	427	78	136	30	2	70	69	3	69	7	0	4	7	5	2	.319	.418	.546	.964	*3/DH
16	Dave Nilsson	21	1999	29	MIL	NL	115	404	343	56	106	19	1	62	53	6	64	2	2	4	7	1	2	.309	.400	.554	.954	*2H/D

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 5/11/2014.