Are 14.5% of a team's innings much more important than the rest? Chapman/Miller/Betances

162 games * 9 innings = 1,458 innings

212 innings / 1,458 = 14.5%

212 innings is about the most that the Yankees can reasonably expect from their three monster relief pitchers. Here are their 2015 innings and games, all in relief:

Aroldis Chapman 66, 65 with Cincinnati
Andrew Miller 62, 60
Dellin Betances 84 (most of any pitcher who did not start), 74

66+62+84=212

2015 pitchers with at least 212 innings:

Rk	Player	IP	Year	Age	Tm	Lg	G	GS	CG	SHO	GF	W	L	W-L%	SV	H	R	ER	BB	SO	ERA	FIP	ERA+	HR	BF	AB	2B	3B	IBB	HBP	SH	SF	GDP	SB	CS	PO	BK	WP	BA	OBP	SLG	OPS	OPS+	Pit	Str
1	Clayton Kershaw	232.2	2015	27	LAD	NL	33	33	4	3	0	16	7	.696	0	163	62	55	42	301	2.13	1.99	175	15	890	839	26	2	1	5	4	0	8	7	9	9	3	9	.194	.237	.284	.521	49	3392	2303
2	Dallas Keuchel	232.0	2015	27	HOU	AL	33	33	3	2	0	20	8	.714	0	185	68	64	51	216	2.48	2.91	162	17	911	854	28	2	0	2	1	3	21	5	0	0	0	9	.217	.262	.314	.575	58	3492	2203
3	Jake Arrieta	229.0	2015	29	CHC	NL	33	33	4	3	0	22	6	.786	0	150	52	45	48	236	1.77	2.35	222	10	870	811	32	4	2	6	4	1	15	27	6	1	0	6	.185	.236	.271	.507	43	3438	2236
4	Max Scherzer	228.2	2015	30	WSN	NL	33	33	4	3	0	14	12	.538	0	176	74	71	34	276	2.79	2.77	144	27	899	847	40	3	2	5	11	2	5	6	2	0	1	10	.208	.242	.358	.600	63	3359	2380
5	Zack Greinke	222.2	2015	31	LAD	NL	32	32	1	0	0	19	3	.864	0	148	43	41	40	200	1.66	2.76	225	14	843	790	22	3	1	5	6	2	15	7	6	2	0	7	.187	.231	.276	.507	45	3239	2078
6	Corey Kluber	222.0	2015	29	CLE	AL	32	32	4	0	0	9	16	.360	0	189	92	86	45	245	3.49	2.97	122	22	886	819	45	2	3	11	7	4	18	16	7	0	1	6	.231	.279	.371	.650	73	3273	2231
7	David Price	220.1	2015	29	TOT	AL	32	32	3	1	0	18	5	.783	0	190	70	60	47	225	2.45	2.78	161	17	888	826	40	4	2	3	4	8	17	0	2	1	0	4	.230	.271	.350	.621	71	3388	2322
8	Madison Bumgarner	218.1	2015	25	SFG	NL	32	32	4	2	0	18	9	.667	0	181	73	71	39	234	2.93	2.87	129	21	869	814	30	5	2	7	5	4	11	5	4	1	0	1	.222	.263	.349	.612	73	3312	2210
9	John Lackey	218.0	2015	36	STL	NL	33	33	1	0	0	13	10	.565	0	211	71	67	53	175	2.77	3.57	143	21	896	824	32	2	5	4	11	4	29	9	3	0	3	5	.256	.303	.376	.679	89	3127	2139
10	R.A. Dickey	214.1	2015	40	TOR	AL	33	33	2	0	0	11	11	.500	0	195	97	93	61	126	3.91	4.48	101	25	884	798	37	8	1	11	3	11	18	6	4	3	2	9	.244	.303	.405	.708	94	3264	2144
11	Jeff Samardzija	214.0	2015	30	CHW	AL	32	32	2	2	0	11	13	.458	0	228	122	118	49	163	4.96	4.23	79	29	910	836	40	9	0	12	4	9	17	12	4	0	0	5	.273	.319	.446	.765	112	3339	2242
12	Cole Hamels	212.1	2015	31	TOT	ML	32	32	2	1	0	13	8	.619	0	190	88	86	62	215	3.65	3.47	112	22	880	800	35	2	3	10	6	2	19	24	3	2	4	9	.238	.300	.369	.669	84	3343	2191
13	Johnny Cueto	212.0	2015	29	TOT	ML	32	32	2	2	0	11	13	.458	0	194	87	81	46	176	3.44	3.53	117	21	866	803	44	5	1	8	5	4	18	3	2	1	4	0	.242	.288	.387	.675	86	3268	2148
14	Chris Archer	212.0	2015	26	TBR	AL	34	34	1	1	0	12	13	.480	0	175	85	76	66	252	3.23	2.90	122	19	868	795	31	0	0	3	2	2	10	7	8	0	0	13	.220	.282	.331	.613	71	3449	2241

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 2/10/2016.

Would you trade Chapman/Miller/Betances for one of the starters above? For Kershaw or Greinke?

The most games that the three relievers can pitch together would be about 60. Kershaw or Greinke could start about 32 games, about half. There's no simple formula for comparing, but some general points:
- trading three for one introduces a single point of failure, if the one gets injured
- the three can have the most impact in specific games if all three pitch: high impact in one third of the innings in 60 games; other scenarios are scattered
- the one starting pitcher can have somewhat less impact on seven innings (77%) of a bit more than half as many games.

I'd trade Chapman/Miller/Betances for Kershaw or Greinke in a minute. How about you?