Baseball BeatJanuary 09, 2007
Categorizing Pitchers (Part Two): Relievers
By Rich Lederer

As a follow-up to yesterday's Categorizing Pitchers by Batted Ball Types and Strikeout Rates (which focused on starters), today's article is devoted exclusively to relievers.

The graph below includes strikeout and groundball data for every reliever in the majors (defined for this exercise as those with 30 or more innings who started less than one-third of the time). The y-axis is groundball percentage (GB%) and the x-axis is strikeouts per batter faced (K/BF). There are four quadrants with the mid-point equal to the average GB% of 43.30% and average K/BF of 18.63% for relievers. By comparison, starters had a mean GB% and K/BF rates of 43.8% and 15.88%, respectively. Interestingly, while the groundball rates were virtually the same, the average strikeout rate among relievers was 2.75 percentage points higher or 17.3%.

Reliever-GBK.png

Graph courtesy of David Appelman, FanGraphs.

The average ERA among all qualifiers was 3.90. The average ERA for relievers with above-average K rates was 3.67. The average ERA for those with below-average K rates was 4.13. Similarly, the average ERA for relievers with above-average GB rates was 3.93, while the average ERA for those with below-average GB rates was 3.88.

The average ERA by quadrants:

       W        E
N     4.12     3.55
S     4.14     3.73          

As shown, it appears as if groundball rates do not positively impact ERA for relievers - at least not in 2006. Instead, it's all about strikeouts. This is potentially a very interesting and enlightening conclusion.

The various results are also much tighter. As one would expect, the average ERA for each type was lower across the board for relievers than starters. But the disparity in average ERA between relievers with above-average and below-average K and GB rates is not as significant as it was for starters.

ERA is far from foolproof as a measurement of a relief pitcher's effectiveness. Win Probability Added (WPA) is arguably a better metric to use when evaluating relievers. That said, reliever ERA isn't worthless and is a decent indicator of performance.

Let's take a closer look at the results, beginning with the northeast quadrant and going clockwise. The pitchers are sorted by K/BF rates in the first three tables and by GB% in the last table.

NORTHEAST QUADRANT (ABOVE-AVG GB AND K RATES)

Name                    GB%     K/BF
J.J. Putz               50.55%  34.32%
Billy Wagner            52.84%  31.65%
Brad Lidge              43.85%  30.59%
Hong-Chih Kuo           44.30%  27.52%
Tom Gordon              45.28%  26.88%
Bobby Jenks             58.79%  26.67%
Luis Vizcaino           45.12%  26.47%
Taylor Tankersley       44.00%  25.84%
Dennys Reyes            68.99%  25.26%
Mike Wuertz             53.64%  24.00%
Scot Shields            51.93%  23.93%
Scott Williamson        50.00%  23.86%
Adam Wainwright         47.55%  23.30%
Greg Aquino             47.86%  23.18%
C.J. Wilson             49.18%  22.51%
John Grabow             48.97%  21.78%
Matt Thornton           49.33%  21.59%
Ambiorix Burgos         43.32%  21.43%
Fernando Rodney         56.54%  21.38%
Tim Hamulack            48.04%  21.12%
Pedro Feliciano         49.43%  21.09%
Heath Bell              50.85%  21.08%
Juan Rincon             50.92%  20.63%
Aaron Heilman           44.86%  20.51%
Akinori Otsuka          52.33%  20.26%
Jason Isringhausen      43.83%  20.23%
Cla Meredith            68.84%  20.00%
Manuel Corpas           45.45%  19.85%
Joe Kennedy             48.57%  19.59%
Ryan Dempster           51.74%  19.59%
Duaner Sanchez          52.32%  19.21%
Brendan Donnelly        43.62%  19.06%
Mariano Rivera          53.92%  18.77%
Scott Downs             55.60%  18.65%

As shown in the graph, J.J. Putz, Billy Wagner, Bobby Jenks, Dennys Reyes, and Cla Meredith stand out as outliers with significantly higher strikeout and/or groundball rates than the others. Brad Lidge's K rate (30.59%) is worth pointing out. I wouldn't give up on him. He pitched much better on the road (.202/.311/.271) than at home (.267/.350/.509). Anyone who dominated hitters the way he did away from Minute Maid Park can pitch on my team.

SOUTHEAST QUADRANT (BELOW-AVG GB AND ABOVE-AVG K RATES)

Name                    GB%     K/BF
Patrick Neshek          31.58%  38.41%
Joe Nathan              35.62%  36.26%
Takashi Saito           35.50%  35.31%
Francisco Rodriguez     38.55%  33.11%
B.J. Ryan               36.65%  31.85%
Jose Valverde           35.43%  30.94%
Jorge Julio             40.25%  30.88%
Jonathan Broxton        39.25%  30.31%
Jonathan Papelbon       37.35%  29.18%
Logan Kensing           28.57%  27.95%
Kiko Calero             34.90%  27.80%
Fernando Cabrera        33.33%  27.73%
Joel Zumaya             33.98%  27.71%
Scott Eyre              41.77%  27.44%
Mike Gonzalez           36.64%  27.35%
Trever Miller           32.58%  27.05%
Rafael Soriano          27.15%  26.97%
Scott Cassidy           35.51%  26.92%
Brian Sikorski          29.47%  26.76%
Brian Fuentes           34.73%  26.64%
Francisco Cordero       40.10%  26.09%
Kyle Farnsworth         34.25%  25.95%
Derrick Turnbow         42.38%  25.94%
Will Ohman              33.53%  25.87%
Justin Speier           30.07%  24.77%
Damaso Marte            33.80%  24.71%
Joaquin Benoit          37.27%  24.50%
George Sherrill         30.30%  24.14%
Alan Embree             42.95%  23.98%
Jason Frasor            42.66%  23.72%
Eddie Guardado          32.73%  23.49%
Huston Street           36.95%  23.10%
Dan Wheeler             36.55%  23.05%
Joe Nelson              34.45%  22.80%
Justin Duchscherer      36.88%  22.77%
Ron Mahay               40.63%  22.76%
Bob Howry               37.79%  22.61%
Tyler Johnson           38.78%  22.56%
Rick Helling            30.11%  22.54%
Chad Cordero            35.32%  22.48%
Jon Rauch               30.20%  22.45%
Arthur Rhodes           36.43%  22.43%
David Aardsma           36.99%  21.78%
Rudy Seanez             30.63%  21.69%
Scott Linebrink         39.37%  21.66%
Jimmy Gobble            38.04%  21.62%
Ramon Ramirez           40.72%  21.40%
Tyler Yates             41.18%  21.20%
Joe Borowski            32.50%  21.05%
Vinnie Chulk            43.07%  20.98%
Scott Proctor           33.00%  20.89%
Kevin Gregg             35.66%  20.82%
Rafael Betancourt       23.35%  20.78%
Emiliano Fruto          37.14%  20.61%
Randy Flores            39.06%  20.41%
Trevor Hoffman          32.24%  20.16%
Kurt Birkins            43.02%  19.85%
Ron Villone             30.74%  19.73%
Aaron Fultz             38.18%  19.56%
Brandon McCarthy        38.46%  19.49%
Kevin Correia           34.12%  19.32%
Russ Springer           27.06%  19.17%
Chris Ray               35.33%  19.10%
Guillermo Mota          34.12%  19.09%
Scott Dohmann           39.58%  19.05%
Jamie Walker            30.61%  18.88%
Joel Peralta            31.72%  18.75%
Jose Capellan           32.06%  18.71%
Andy Sisco              39.23%  18.71%

The outliers depict why Minnesota's bullpen was so effective last year. Just as Reyes was one of the standouts in the NE quadrant, Patrick Neshek and Joe Nathan head the group of relievers with above-average strikeout and below-average groundball rates. Add Juan Rincon (50.92% GB and 20.63% K/BF) and Jesse Crain (55.19%/18.46%) to the mix and the Twins received 307 relief innings at an ERA of 2.35.

SOUTHWEST QUADRANT (BELOW-AVG GB AND K RATES)

Name                    GB%     K/BF
Christopher Britton     31.06%  18.55%
Jeremy Accardo          42.27%  18.18%
Armando Benitez         32.20%  18.13%
Bob Wickman             41.76%  18.03%
Jonathan Sanchez        35.77%  17.84%
Jason Bergmann          31.55%  17.82%
Keith Foulke            24.05%  17.56%
Chad Paronto            42.60%  17.30%
Neal Cotts              42.29%  17.13%
Fernando Nieve          40.97%  17.03%
Matt Capps              40.65%  17.02%
Jeremi Gonzalez         30.77%  16.92%
Bryan Corey             40.34%  16.87%
Ken Ray                 36.89%  16.72%
Mike Stanton            42.11%  16.55%
Randy Messenger         38.38%  16.36%
Travis Harper           37.24%  16.33%
Brian Tallet            40.76%  16.16%
Roberto Novoa           42.56%  15.77%
Brandon Lyon            42.86%  15.70%
Tony Pena               39.22%  15.56%
Josh Hancock            40.08%  15.48%
Bruce Chen              32.56%  15.45%
Danys Baez              39.68%  15.18%
Ryan Vogelsong          38.02%  15.17%
Esteban Yan             42.98%  14.91%
Brandon Medders         41.88%  14.87%
David Riske             35.97%  14.81%
Wil Ledezma             33.51%  14.77%
Roman Colon             40.31%  14.71%
Fabio Castro            38.89%  14.40%
Jorge Sosa              35.34%  14.31%
Jake Woods              41.95%  13.95%
Chad Gaudin             39.49%  13.04%
Jon Adkins              40.70%  12.93%
Julio Mateo             23.63%  12.86%
Danny Miceli            42.42%  12.68%
Brian Meadows           38.13%  11.25%
Mike Timlin             39.65%  10.75%
Brian Sweeney           39.27%   9.70%
Sendy Rleal             40.13%   9.36%

Except for a few closers who have fallen from grace, this is a pretty non-descript group of pitchers. I don't think I would want to bank on any of these relievers. Sendy Rleal should give thanks for having had the opportunity to pitch in the big leagues last year. It would be one thing if he was a left-hander but a RHP with a K/BF rate of less than 10% has almost no chance to survive at this level.

NORTHWEST QUADRANT (ABOVE-AVG GB AND BELOW-AVG K RATES)

Name                    GB%     K/BF
Brandon League          72.87%  16.76%
Wes Littleton           70.75%  12.32%
Chad Bradford           63.30%  17.86%
Ryan Wagner             62.00%  14.18%
Rick White              60.98%  14.49%
Chad Qualls             60.00%  15.73%
Fausto Carmona          59.58%  17.06%
Scott Feldman           59.06%  17.14%
Todd Williams           57.56%   9.23%
Sean Green              57.55%  10.79%
Scott Schoeneweis       57.50%  13.12%
Shawn Camp              57.32%  16.16%
Julian Tavarez          57.01%  12.99%
J.C. Romero             56.97%  13.72%
Joe Beimel              56.78%  10.17%
Salomon Torres          55.24%  17.52%
Jesse Crain             55.19%  18.46%
Brad Thompson           55.14%  13.06%
Chad Harville           53.49%  16.30%
Christopher Sampson     53.27%  11.54%
Todd Jones              52.94%  10.29%
Gary Majewski           52.77%  13.61%
Rick Bauer              52.77%  11.59%
Ray King                52.67%  11.56%
Edwin Jackson           52.10%  15.52%
Mike Wood               52.05%   9.45%
Todd Coffey             52.03%  17.65%
Danny Kolb              51.22%  12.21%
Brian Shouse            51.20%  13.22%
Hector Carrasco         50.00%  17.27%
Geoff Geary             50.00%  15.38%
Lance Cormier           50.00%  12.91%
Jeremy Affeldt          49.70%  10.71%
Braden Looper           49.36%  13.31%
Tom Martin              49.20%  17.29%
Jon Switzer             49.14%  11.46%
Todd Wellemeyer         48.92%  15.65%
Jason Davis             48.66%  15.04%
Matt Belisle            48.06%  14.44%
Darren Oliver           47.76%  18.02%
Mike Myers              47.42%  16.67%
Macay McBride           47.31%  18.47%
Steve Kline             47.20%  14.54%
Jason Grilli            47.09%  11.48%
Ryan Franklin           47.06%  12.54%
Roberto Hernandez       46.97%  16.84%
Matt Herges             46.88%  10.98%
Oscar Villarreal        46.86%  13.85%
Dave Borkowski          46.58%  17.39%
Jose Mesa               46.32%  12.38%
Saul Rivera             46.11%  14.80%
William Eyre            45.62%   9.45%
Elmer Dessens           45.28%  15.57%
Rheal Cormier           45.28%   9.27%
Matt Guerrier           44.96%  12.33%
Matt Wise               44.93%  14.36%
Manny Delcarmen         44.57%  18.52%
David Weathers          44.55%  15.92%
LaTroy Hawkins          44.24%  10.34%
Ruddy Lugo              43.91%  13.22%
Bill Bray               43.83%  17.49%
Brad Halsey             43.61%  12.30%
Craig Hansen            43.55%  17.05%

Brandon League is intriguing. The groundball specialist could become a highly effective set-up man or perhaps even a closer if he can improve his K rate from 16.76% toward 20%. He made huge strides in 2006 and won't turn 24 until March. League was death on RHB (.178/.239/.238) and handled LHB (.276/.323/.362) admirably as well.

In addition to the notes I made at the end of yesterday's article, be aware of the small sample size caveat when it comes to relief pitchers. However, the aggregate results are statistically relevant with more than 10,000 innings measured.

Comments

Brandon League will be replacing Speier as BJ Ryan's setup man in Toronto. Some see the second coming of Duane Ward.

Rich,

Great stuff, once again.
I would also like to see how GB% affects inherited runners scored %. It would seem to be a given that K% has an inverse correlation with inherited runners scored %, but I'm not sure how GB% would relate (in lieu of the above data). I would certainly think that GIDP would play a factor, but bringing the infield in and other late-and-close game strategies might have unpredictable effects, as well.

Wow. Dennys Reyes. Honestly, I had no idea.

"Some see the second coming of Duane Ward."

And they all live in Toronto?

For the most part the hype about relief prospects is disappointing. Jose Cappellan. Joey Devine. Craig Hansen. Santiago Casilla/Jairo Garcia/Dr. Van Nostrum.