Starters with W

I was just bored at a Starbucks waiting for my parents, decided to answer one of the questions I had for quite a long time. If the Yankees had a x-win season, how many of them were won by the starters?

I went to the baseball-reference and searched for situations where starters took the wins in 2014. Obviously the number of total wins at MLB in a season is 162*30/2 = 2430, which is the same number as the number of total games in a season.

There were 236 starters (about 8 per team) with at least one win, and the number of total wins by them was 1706. An average does not mean much in this case, but on average a starter won 7.23 games. Thus, about 70.2% of the games were won by the starters in 2014.

One way of looking at it would be, if the Yankees want to have 90-win, the starters should win about 63 games. It doesn't seem too hard, does it? If Tanaka, Pineda stay healthy and combine 30+ wins, it will look even easier.

I was wondering if that ratio is much different from a team to another.

Team	W from starters	Wins	ratio
CIN	65	76	0.855
LAD	76	94	0.809
TOR	63	83	0.759
DET	68	90	0.756
MIL	61	82	0.744
ATL	58	79	0.734
WSH	70	96	0.729
SDP	56	77	0.727
NYM	57	79	0.722
HOU	50	70	0.714
SEA	62	87	0.713
STL	64	90	0.711
BAL	68	96	0.708
OAK	62	88	0.705
BOS	50	71	0.704
NYY	59	84	0.702
TBR	54	77	0.701
LAA	68	98	0.694
TEX	46	67	0.687
MIN	48	70	0.686
KCR	61	89	0.685
CHC	50	73	0.685
CHW	50	73	0.685
COL	44	66	0.667
PHI	47	73	0.644
ARI	41	64	0.641
SFG	56	88	0.636
PIT	55	88	0.625
MIA	47	77	0.61
CLE	50	85	0.588
total	1706	2430	0.702

Other than CIN, LAD, and CLE, every team was between .600 and .800. Especially, 14 out of 30 teams including the Yankees were between .685 and .715, which was pretty intriguing.

I was wondering if the ratio would be similar in the postseason. Out of 26 wins (2 wins in WC, 12 wins in DS, 8 wins in CS, and 4 wins in WS,) only 13 of them (50%) were attained by the starters! It could be because of a small sample size, so I took 5 postseasons to have about one regular season (=162 games.) From 2010 - 2014, There were 177 postseason games, and 108 wins (61.0%) were attained by the starters.

It is not particularly surprising, because mangers tend to pull out their starters earlier in the postseason games than they do in regular season games. 126 losses out of 177 games (71.2%) which matches with 1720 losses out of 2430 games (70.8%) in the regular season of 2014. Still, it was fun to dig up that data!