Relief Pitcher Handedness Platoon Splits

One relief pitcher trait I like to have on hand during draft season is how much of a split has a pitcher displayed over his career against right- and left-handed hitters. Most teams don’t want their closer to have a large split because with all hands on deck in the ninth, the opposing manager will use up all his available platoon options. The reason a pitcher may or may not have a split may be many, but truthfully I don’t have time to evaluate each relief pitcher in detail (and still stay married) so I use this nice little cheat sheet.

I examined which pitchers have historically small or large handedness splits and how much to take them into account when valuing the relief pitcher for a closer’s role.

Here are the traits I look to calculated the splits:

vsLHH-vsRHH K% – BB%: A little confusing heading, but fairly simple. First I take the pitchers’ K% minus his BB% against both left-handed (LHH) and right-handed (RHH) hitters. Then, I subtract his LHH value from his RHH value. A negative value means the pitcher struggles against LHH and a positive value means they struggle against RHH.

Here is an example walkthrough using Aroldis Chapman

vs LHH
K%: 47.9%
BB%: 10.6%

vs RHH
K%: 38.3%
BB%: 13.0%

Final equation: (47.9%-10.6%) – (38.3%-13.0%) = 37.3% – 25.3% = 12.0% (rounding difference from the final sheet)

Career K%-BB%: Just a measure of a pitcher’s true talent level. One issue is I didn’t look at starting vs relief stats. Just keep it in mind for pitchers like Luke Hochevar who had increased success since moving to the bullpen.

vsLHH-vsRHH HR9: Just like “vsLHH-vsRHH K% – BB%” I am looking at the pitcher’s propensity to give up home runs depending of the hitter handedness. Again, a negative value means the pitcher struggles against LHH and a positive value means they struggle against RHH.

Total Talent Factor: This equation is pretty simple, It is:

“Career K%-BB%” minus the absolute value of “vsLHH-vsRHH K% – BB%”

This is the value I look at for a pitcher’s total talent. For a pitcher like Chapman, he performs worse against RHH, but his performance is batter than most pitchers against righties.

Fake_RA_vsRHH and vsLHH: First, these value are suspect to say the least. It is the Runs allowed per nine innings when a certain handed batter is hitting. A pitcher may have walked three LHH and then a RHH doubles them all in. The pitcher struggled more against LHH, but the runs came against a RHH. With that said, it does give some idea of how many runs the pitcher has allowed against LHH and RHH.

Enough of the details, time for data. Here is the top and bottom 10 pitchers (min 50 career innings) with the largest and smallest absolute value of “vsLHH-vsRHH K% – BB%”. I did keep the output in negative and positive values so which handed batter the pitcher struggles against can be known. And again, a negative value means the pitcher struggles against LHH and a positive value means they struggle against RHH (full list here).

Name	Throws	Seasons	vsLHH-vsRHH K%-BB%	Career K%-BB%	vsLHH-vsRHH HR9	Total_Talent_Factor	Fake_ERA_vsLHH	Fake_ERA_vsRHH
Scott Rice	L	1	30.1%	8.6%	0.24	-21.5%	1.70	9.64
Vinnie Pestano	R	4	-22.3%	19.1%	0.57	-3.2%	4.01	2.07
Josh Outman	L	5	21.6%	9.8%	-0.58	-11.8%	3.16	5.99
Paco Rodriguez	L	2	19.3%	22.3%	-1.11	3.0%	0.79	4.47
Sergio Romo	R	6	-19.3%	24.6%	-0.22	5.3%	2.59	2.55
Brian Matusz	L	5	18.2%	11.0%	-0.32	-7.2%	4.45	5.92
Alex Torres	L	2	18.1%	17.9%	-0.23	-0.2%	2.40	2.07
Randy Choate	L	10	17.3%	13.1%	-0.36	-4.3%	2.70	7.60
Carter Capps	R	2	-16.7%	17.1%	1.08	0.4%	6.15	4.58
Al Alburquerque	R	3	15.9%	20.9%	-0.07	4.9%	3.51	2.59
Bryan Morris	R	2	0.3%	6.3%	0.34	6.0%	3.09	3.81
Pedro Strop	R	5	-0.3%	11.4%	-0.24	11.0%	4.66	3.36
Tim Stauffer	R	8	-0.3%	9.8%	-0.05	9.5%	3.84	4.42
John Axford	R	5	-0.3%	18.5%	-0.38	18.3%	3.13	4.29
Rich Hill	L	9	0.2%	11.7%	-0.62	11.5%	4.20	5.38
Drew Storen	R	4	0.2%	16.3%	-0.05	16.1%	3.63	3.70
Mike Adams	R	9	0.2%	18.0%	-0.32	17.8%	2.72	2.62
Trevor Rosenthal	R	2	0.2%	26.5%	-0.62	26.3%	2.29	3.49
Francisco Rodriguez	R	12	-0.1%	20.5%	0.29	20.3%	3.19	2.73
Jonathan Papelbon	R	9	0.1%	23.3%	-0.03	23.2%	2.60	2.94

Vinnie Pestano’s name showing up is interesting. Before the Indians signed John Axford, Pestano was in the Indians closer and setup man conversation. Historically, Pestano just has not been able to get lefties out. Pestano has allowed LHH to post a .349 wOBA against him in his career versus a .236 wOBA posted by righties. Pestano has basically been a ROOGY.

Now here are the top and bottom ten relief pitchers a according to Total Talent Factor (min 50 IP)

Name	Throws	Total_Talent_Factor	vsLHH-vsRHH K%-BB%	Career K%-BB%	vsLHH-vsRHH HR9	Fake_ERA_vsLHH	Fake_ERA_vsRHH
Craig Kimbrel	R	33.6%	0.9%	34.5%	-0.16	1.60	1.43
Koji Uehara	R	26.7%	0.7%	27.4%	0.08	2.17	3.05
Trevor Rosenthal	R	26.3%	0.2%	26.5%	-0.62	2.29	3.49
Greg Holland	R	25.7%	-0.4%	26.1%	-0.38	2.42	2.75
Jonathan Papelbon	R	23.2%	0.1%	23.3%	-0.03	2.60	2.94
Jake McGee	L	21.6%	-2.0%	23.6%	0.13	3.13	3.56
Danny Farquhar	R	21.5%	4.0%	25.5%	-0.04	4.47	6.16
Kenley Jansen	R	21.5%	-9.5%	31.0%	-0.12	2.29	2.07
Joe Nathan	R	21.3%	-2.2%	23.5%	0.15	2.81	1.98
Francisco Rodriguez	R	20.3%	-0.1%	20.5%	0.29	3.19	2.73
Burke Badenhop	R	-3.1%	-14.7%	11.7%	0.22	5.46	3.78
Vinnie Pestano	R	-3.2%	-22.3%	19.1%	0.57	4.01	2.07
Mitchell Boggs	R	-3.3%	-10.6%	7.2%	0.31	5.51	3.85
Henry Rodriguez	R	-3.5%	-10.9%	7.4%	0.06	4.98	4.81
Randy Choate	L	-4.3%	17.3%	13.1%	-0.36	2.70	7.6
Jared Hughes	R	-4.5%	-13.6%	9.1%	0.31	5.71	2.82
Donnie Veal	L	-5.1%	14.7%	9.6%	-0.56	3.53	6.64
Brian Matusz	L	-7.2%	18.2%	11.0%	-0.32	4.45	5.92
Josh Outman	L	-11.8%	21.6%	9.8%	-0.58	3.16	5.99
Scott Rice	L	-21.5%	30.1%	8.6%	0.24	1.70	9.64

The top list of relievers are pretty much all closers. The bottom list of pitchers can be useful, but it may only be in a ROOGY or LOOGY role.

One name which sticks out is Jake McGee. He is the only left-handed pitcher on the top list. Second, he really struggled last year when runners where in scoring position allowing a .361 wOBA. With just runners on base, his wOBA allowed was only .282. He seems to be able to pitch decently from the stretch. He looks to be a nice 2014 bounce back candidate and possibly even the Rays closer.

A closer needs to have the ability to get out hitters from both sides of the plate at an extraordinary rate. By looking at a reliever’s historic left and right splits, the difference can be calculated.