Factoring Bullpens Into DFS Decisions

About three or four times each week I create projections and player rankings for DFS contests. As an example, you can find my breakdown of tonight’s DFS action here ($). My projections start with the rest-of-season ZiPS projections, which I break down to a per-game basis. I then adjust each projection for matchup and ball park.

For hitters, the matchup adjustment is based on the wOBA allowed by the starting pitcher they will be facing against hitters of the same handedness since the start of the 2014 season. When small sample sizes apply, I manually set the matchup adjustment. But it recently occurred to me that adjustments for matchup should probably include the strength of the opponent’s bullpen. To date, starters are pitching an average of 5.88 innings per game this year, meaning my matchup adjustment is ignoring roughly a third of each hitter’s plate appearances.

Unfortunately, our team leaderboards will not split up bullpen performance against left and right handed batters, but we should still be able to look at a bullpen’s overall results so far and identify additional matchup advantages. To examine this, I simply took each bullpen’s performance to date and calculated how many fantasy points they are allowing to opposing hitters per batter faced. For the sake of this post, I used the DraftKings scoring system.

Team	Pts/BF	Factor
White Sox	1.43	1.14
Rangers	1.38	1.10
Phillies	1.37	1.09
Rockies	1.36	1.09
Athletics	1.36	1.09
Braves	1.35	1.08
Red Sox	1.33	1.06
Diamondbacks	1.32	1.06
Twins	1.32	1.05
Nationals	1.31	1.04
Reds	1.31	1.04
Mariners	1.30	1.04
Indians	1.29	1.02
Padres	1.28	1.02
Marlins	1.28	1.02
Rays	1.27	1.01
Tigers	1.27	1.01
Cubs	1.25	1.00
Brewers	1.25	0.99
Angels	1.22	0.98
Pirates	1.22	0.97
Giants	1.21	0.96
Dodgers	1.17	0.93
Orioles	1.16	0.93
Blue Jays	1.16	0.93
Yankees	1.16	0.92
Mets	1.15	0.92
Cardinals	1.13	0.90
Royals	1.01	0.81
Astros	0.99	0.79

This doesn’t exactly line up with traditional stats like ERA, but it’s fairly close. Five of the six worst bullpens in ERA are among the six worst bullpens in terms of fantasy points allowed per batter faced.

Let’s apply this to the 10-game evening slate tonight. First I’ll show you the matchup factors I created to adjust hitter projections based solely on the quality of the opposing starter. Then we’ll compare that to how those factors differ if we include the strength of an opponent’s bullpen.

Name	Throws	Opp	wOBA v. L	Factor		Name	Throws	Opp	wOBA v. R	Factor
Jeremy Guthrie	R	Mil	0.379	1.20		CC Sabathia	L	Mia	0.355	1.16
Colby Lewis	R	LAD	0.368	1.16		Justin Verlander	R	Cin	0.35	1.15
Ryan Vogelsong	R	Sea	0.363	1.15		Danny Salazar	R	ChC	0.335	1.10
Jimmy Nelson	R	KC	0.362	1.14		R.A. Dickey	R	NYM	0.33	1.08
Mike Leake	R	Det	0.348	1.10		Colby Lewis	R	LAD	0.329	1.08
Clay Buchholz	R	Atl	0.328	1.04		Clay Buchholz	R	Atl	0.322	1.05
Michael Montgomery	L	SF	0.317	1.00		Michael Montgomery	L	SF	0.32	1.05
Mat Latos	R	NYY	0.312	0.98		Bartolo Colon	R	Tor	0.317	1.04
Jeff Samardzija	R	Pit	0.312	0.98		Mat Latos	R	NYY	0.306	1.00
Bartolo Colon	R	Tor	0.311	0.98		Ryan Vogelsong	R	Sea	0.294	0.96
Doug Fister	R	TB	0.310	0.98		Jimmy Nelson	R	KC	0.294	0.96
R.A. Dickey	R	NYM	0.308	0.97		Mike Leake	R	Det	0.293	0.96
Gerrit Cole	R	CWS	0.306	0.97		Jeff Samardzija	R	Pit	0.291	0.95
Justin Verlander	R	Cin	0.305	0.96		Chris Archer	R	Was	0.29	0.95
Danny Salazar	R	ChC	0.303	0.96		Doug Fister	R	TB	0.288	0.94
Jason Hammel	R	Cle	0.299	0.94		Gerrit Cole	R	CWS	0.284	0.93
Shelby Miller	R	Bos	0.298	0.94		Zack Greinke	R	Tex	0.284	0.93
Zack Greinke	R	Tex	0.276	0.87		Shelby Miller	R	Bos	0.282	0.92
Chris Archer	R	Was	0.268	0.85		Jason Hammel	R	Cle	0.276	0.90
CC Sabathia	L	Mia	0.265	0.84		Jeremy Guthrie	R	Mil	0.273	0.89

Alright, now let’s compare the chart above to a matchup factor that inlcudes a bullpen component. For simplicity’s sake, I’ve weighted the total matchup component two-thirds for the starter and one-third for the bullpen. I could get much more specific about the weights based on each starter’s average length of start as well as expected game flow based on Vegas lines, but we’ll keep it simple for this post.

Name	Team	Opp	SP Factor	BP Factor	Total		Name	Team	Opp	SP Factor	BP Factor	Total
Colby Lewis	Tex	LAD	1.16	1.10	1.14		Justin Verlander	Det	Cin	1.15	1.01	1.10
Jimmy Nelson	Mil	KC	1.14	0.99	1.09		Colby Lewis	Tex	LAD	1.08	1.10	1.09
Ryan Vogelsong	SF	Sea	1.15	0.96	1.09		CC Sabathia	NYY	Mia	1.16	0.92	1.08
Mike Leake	Cin	Det	1.10	1.04	1.08		Danny Salazar	Cle	ChC	1.10	1.02	1.07
Jeremy Guthrie	KC	Mil	1.20	0.81	1.07		Clay Buchholz	Bos	Atl	1.05	1.06	1.06
Clay Buchholz	Bos	Atl	1.04	1.06	1.04		Michael Montgomery	Sea	SF	1.05	1.04	1.04
Jeff Samardzija	CWS	Pit	0.98	1.14	1.04		R.A. Dickey	Tor	NYM	1.08	0.93	1.03
Michael Montgomery	Sea	SF	1.00	1.04	1.01		Jeff Samardzija	CWS	Pit	0.95	1.14	1.01
Doug Fister	Was	TB	0.98	1.04	1.00		Mat Latos	Mia	NYY	1.00	1.02	1.01
Mat Latos	Mia	NYY	0.98	1.02	1.00		Bartolo Colon	NYM	Tor	1.04	0.92	1.00
Shelby Miller	Atl	Bos	0.94	1.08	0.99		Mike Leake	Cin	Det	0.96	1.04	0.99
Danny Salazar	Cle	ChC	0.96	1.02	0.98		Doug Fister	Was	TB	0.94	1.04	0.98
Justin Verlander	Det	Cin	0.96	1.01	0.98		Shelby Miller	Atl	Bos	0.92	1.08	0.97
Gerrit Cole	Pit	CWS	0.97	0.97	0.97		Jimmy Nelson	Mil	KC	0.96	0.99	0.97
Jason Hammel	ChC	Cle	0.94	1.00	0.96		Chris Archer	TB	Was	0.95	1.01	0.97
Bartolo Colon	NYM	Tor	0.98	0.92	0.96		Ryan Vogelsong	SF	Sea	0.96	0.96	0.96
R.A. Dickey	Tor	NYM	0.97	0.93	0.96		Gerrit Cole	Pit	CWS	0.93	0.97	0.94
Chris Archer	TB	Was	0.85	1.01	0.90		Jason Hammel	ChC	Cle	0.90	1.00	0.93
Zack Greinke	LAD	Tex	0.87	0.93	0.89		Zack Greinke	LAD	Tex	0.93	0.93	0.93
CC Sabathia	NYY	Mia	0.84	0.92	0.86		Jeremy Guthrie	KC	Mil	0.89	0.81	0.86

As you can see, adding a bullpen factor does result in some noticeable changes. The Dodgers go from having one of the best matchup adjustment factors to having the best factor for their left-handed hitters and second best for their-right-handed hitters. Even if Anthony Ranaudo ends up starting instead of Colby Lewis for Texas, those Dodgers factors will remain atop each list. On the flip side, targeting some bargain Brewers that hit from the left side seemed like the value play of the day when just using Jeremy Guthrie to adjust their projections. But after considering the strong Royals bullpen, they’re less of a consideration.

I realize there are a lot of factors that I’m not considering here. Depending on the game situation, hitters may run into a LOOGY or ROOGY who will present a tough matchup in that plate appearance. And game flow will have an impact on the quality of relievers that enter a game. But on a general basis, having an idea about which bullpens are on the extremes can be useful when making decisions. If nothing else, it can serve as a tie-breaker.