The Pirates Should Carry Two Left-Handers In The 2013 Bullpen

One of the reasons why the Pirates could move Joel Hanrahan is due to the depth in the bullpen; Jason Grilli was signed earlier this winter with a view to close games while the newly acquired Mark Melancon will be the primary setup man. While this will be a popular topic amongst Pirates bloggers since the trade and Tim Williams has comprehensively covered the subject for Pirates Prospects; my argument is why the Pirates need to be carrying two left-handed pitchers in the bullpen this season.

When looking at the subject, I have only reviewed the major league statistics of relievers/those likely competing for a role in the bullpen (such as Vin Mazzaro) that have completed more than 30 innings in the majors over the last two years. This therefore excludes Bryan Morris, Rick VandenHurk, Justin Wilson and Andy Oliver. I also elected to omit Kyle McPherson and Jeff Locke, as I believe that whoever loses the battle for the fifth rotation spot will be the next in line in the minor leagues – at least until Gerrit Cole is ready. 

This leaves seven pitchers on the 40-man roster, six right-handers – Grilli, Melancon, Jared Hughes, Chris Leroux, Vin Mazzaro and Zach Stewart – and Tony Watson as the lone lefty. Grilli, Melancon, Hughes, Watson (as well as Morris) are locks for the bullpen, leaving two open spots. Leroux, Mazzaro and VandenHurk are out of options so will have the advantage – otherwise they will have to be placed on waivers. However, as I believe that two lefties should be in the bullpen, it would then leave one open spot available. 

Looking at each player’s FIP over the last two seasons, players with traditional splits have a wide gap both Grilli and Leroux have reverse splits; although it has to be noted that Leroux has not only pitched the fewest innings, he has benefited from not giving up a home run to a left-hander:

		FIP v Left	FIP v Right
	Chris Leroux	1.68	3.30
	Jared Hughes	4.89	3.16
	Jason Grilli	2.38	3.16
	Mark Melancon	4.87	3.02
	Tony Watson	3.23	4.67
	Vin Mazzaro	7.29	4.20
	Zach Stewart	5.26	3.95

In his review of the Hanrahan trade, Keith Law noted that Melancon will struggle with lefties as he lacks a solid changeup, and he does show a large split with a 4.87 FIP against left-handers compared to a 3.02 FIP against right-handers. Using xFIP, as it is a better indicator of future performance, the need for a second left hander is less clear – due to the normalised home run rates. Nonetheless, Hughes, Watson and Mazzaro (although he has mostly been used in a starting role over the last two years) still show big conventional splits:

		xFIP v Left	xFIP v Right
	Chris Leroux	2.62	3.30
	Jared Hughes	4.54	3.16
	Jason Grilli	2.77	3.16
	Mark Melancon	3.59	3.02
	Tony Watson	3.37	4.67
	Vin Mazzaro	6.51	4.20
	Zach Stewart	4.02	3.95

Moving onto each player’s strikeout-per-walk ratio specifically, the addition of a second left-hander to the bullpen becomes more apparent as weaknesses are highlighted. Only Grilli and Leroux (SSS) have ratios above two when facing hitters from both sides of the plate, with Hughes' and Mazzaro’s righty specialism becoming apparent:

		K/BB v Left	K/BB v Right
	Chris Leroux	6.00	3.43
	Jared Hughes	1.08	3.54
	Jason Grilli	2.86	4.27
	Mark Melancon	1.88	4.43
	Tony Watson	2.67	1.79
	Vin Mazzaro	0.58	2.20
	Zach Stewart	1.92	4.33

This can be further analyzed when compared to each pitcher’s strikeout and walk percentages. In the case of Melancon, Watson and, to a lesser extent, Mazzaro, the difference is the spike in walks when facing hitters from the opposite side of the plate, with Watson and Melancon maintaining strong strikeout levels. Hughes is very different however, with his strikeout percentage dropping almost 15% when facing left-handed hitters, highlighting the need to be placed in a ROOGY role:

		K% v Left	K% v Right	BB% v Left	BB% v Right
	Chris Leroux	21.8%	23.3%	3.6%	6.8%
	Jared Hughes	8.6%	23.1%	8.0%	6.5%
	Jason Grilli	37.3%	29.8%	13.0%	7.0%
	Mark Melancon	20.7%	21.7%	11.1%	4.9%
	Tony Watson	23.3%	23.0%	8.7%	12.9%
	Vin Mazzaro	9.2%	12.5%	15.7%	5.7%
	Zach Stewart	11.3%	16.1%	5.9%	3.7%

While Watson maintains a strong strikeout rate against both sets of hitters, his struggles with right handed pitching his highlighted by his batted ball profile as right handed hitters put the ball in the air significantly more often than lefties – with a 26.6 GB% and 55.5 FB% against right-handers and 52.1 GB% and 29.6 FB% when facing left handed hitters. This is something that should also be considered, as with Watson possibly being a lefty specialist then a second left hander in the pen would add more flexibility. 

Leroux may not have pitched many innings in the majors and his strikeout and walks percentages have remained fairly consistent from his minor league numbers, however his balls in play statistics do differ. If he is given the long reliever role next season, more can be learned from his performances. He’s probably the favorite for the role at this point, due to his much stronger swing-and-miss numbers. Both Mazzaro and Stewart have struggled in their trips to the majors, so Stewart is likely going to find a role in the Indianapolis bullpen with Mazzaro designated for assignment.

Many fans question why a closer is not used earlier in games if it’s a point where the game is on the line. This is due to Clint Hurdle's preference for conventional bullpen usage, keeping his closer until save situations, so flexibility in the pen will be required – especially when potential workloads are considered as Watson cannot pitch every day. Given the splits of Hughes and Melancon as well as it being unknown how Morris will adjust to the majors, the second left-hander would provide further depth to the bullpen, as adding a further southpaw would give Hurdle the option of bringing in a LOOGY earlier in the game. Whether this is Justin Wilson, who appears to be better suited for a bullpen role in any case, a different internal option or whether the front office uses some of the remaining payroll budget on a free agent would be determined by management’s confidence in the internal options. However, a pair of left-handed pitchers would be beneficial in the current bullpen, especially when current splits are considered.

All statistics taken from FanGraphs