Categorizing Pitchers by Strikeout and Groundball Rates: Starters - 2007 Edition
It is no secret that the best outcome for a pitcher is a strikeout. There are no ifs, ands, or buts about that statement of fact. That's the way it has always been and that's the way it will always be. Except for the rare missed third strike, a strikeout always produces an out and no chance for runners to advance bases (other than a stolen base).
Among batted ball types, we know that infield flies are the least harmful, followed by groundballs, outfield flies, and line drives. In fact, thanks to researchers like Dave Studeman of The Hardball Times, we can even place a value on the run impact of each event. For example, according to Dave's Batted Balls Redux article in The Hardball Times Baseball Annual 2007, strikeouts had a run impact of -0.113, infield flies -0.088, groundballs 0.045, outfield flies 0.192, and line drives 0.391 per incident in 2006.
Although groundballs generate more hits and errors than flyballs, their run impact is lower because the hits are usually limited to singles and an occasional double down the first or third base line, whereas balls in the air that turn into hits more often become doubles, triples, or home runs. Not only is the run impact from a groundball lower than an outfield fly or line drive but groundball pitchers give up fewer line drives and flyballs. Conversely, pitchers who don't induce as many groundballs allow more line drives and flyballs. One of the basic truths of maintaining a low home run rate is to keep batted balls on the ground. It is also important to note that home run rates tend to fluctuate more than groundball rates because park effects and randomness play a huge role when it comes to the outcome of long flyballs, especially among pitchers.
Based on the above information, it follows that just as pitchers with high strikeout rates would generally fare better than those with low rates, pitchers with high groundball rates would normally fare better than those with low rates (all else being equal). Furthermore, it also suggests that pitchers who combine higher strikeout and groundball rates will outperform those with lower rates.
With the foregoing in mind, in January 2007, I introduced the idea of categorizing starters and relievers by strikeout and groundball rates. Due to the popularity of this series, I have decided to categorize pitchers based on the 2007 data. Like last year, I have greatly benefited from the help of David Appelman of FanGraphs in creating graphs that plot strikeout and groundball rates separately for starters and relievers (featured in part two on Tuesday).
The x-axis is strikeouts per batter faced (K/BF) and the y-axis is groundball percentage (GB%). The graph for the starting pitchers (defined as major leaguers who completed 100 or more innings and started in at least 33% of their appearances) is divided into quadrants with the mid-point equal to the average K/BF of 16.33% and the average GB% of 43.88%. By placing pitchers in quadrants, one can easily ascertain those with above-average strikeout and groundball rates (referred herein as the northeast quadrant), above-average strikeout and below-average groundball rates (southeast quadrant), above-average groundball and below-average strikeout rates (northwest quadrant), and below-average groundball and strikeout rates (southwest quadrant).
Looking at the outliers in the graph is one of the most interesting aspects of this study. Starting with the northeast quadrant and going clockwise, Derek Lowe, Brandon Webb, Felix Hernandez, A.J. Burnett, Erik Bedard, Jake Peavy, Scott Kazmir, Johan Santana, Chris Young, Chuck James, Jason Hirsh, Matthew Chico, Steve Trachsel, Aaron Cook, and Fausto Carmona all stand out for their extreme (good or bad) strikeout and/or groundball rates. Is there anybody who wouldn't take the outliers in the northeast quadrant over the outliers in the southwest quadrant? Lowe (3.88), Webb (3.01), Hernandez (3.92), Burnett (3.75), Bedard (3.16), and Peavy (2.54) all had much lower ERAs than Hirsh (4.81), Chico (4.63), and Trachsel (4.90).
Let's take a closer look at the results. Pitchers in the northeast, southeast, and southwest quadrants are sorted by K/BF rates. Pitchers in the northwest quadrant are listed in the order of GB rates.
NORTHEAST QUADRANT (ABOVE-AVG K AND GB RATES)
Pitcher K/BF GB% Erik Bedard 30.15% 47.87% Jake Peavy 26.73% 44.00% A.J. Burnett 25.47% 54.82% Tim Lincecum 24.27% 47.04% Josh Beckett 23.60% 47.31% John Smoltz 23.09% 44.69% C.C. Sabathia 21.44% 45.00% Dan Haren 20.53% 44.44% Dustin McGowan 20.43% 53.04% Felix Hernandez 20.42% 60.83% Ian Snell 20.07% 45.93% Brandon Webb 19.90% 61.76% Kelvim Escobar 19.70% 44.00% John Lackey 19.27% 44.69% Jeremy Bonderman 19.26% 47.91% Carlos Zambrano 19.14% 46.85% Daniel Cabrera 18.00% 49.51% Jeff Francis 17.90% 44.39% Derek Lowe 17.69% 64.97% Boof Bonser 17.62% 45.05% Chad Gaudin 17.38% 50.97% Mark Hendrickson 17.29% 44.13% Gil Meche 17.22% 46.81% Edwin Jackson 16.95% 45.06% Roy Oswalt 16.92% 52.97% Doug Davis 16.71% 47.02%
There are a number of outstanding arms in the group above. The best of the lot are those with strikeout rates north of 20 and/or groundball rates in the low-50s and above (both of which would be about 20% over the averages). Interestingly, Bedard, Burnett, Josh Beckett, John Smoltz, C.C. Sabathia, Dan Haren, Hernandez, Webb, Kelvim Escobar, Jeremy Bonderman, Carlos Zambrano, Roy Oswalt, and Doug Davis are all northeast quadrant returnees from last season.
Lowe graduated from the northwest quadrant (13.47% K/BF and 67.04% GB in 2006) to the northeast quadrant (17.69% and 64.97%) by improving his strikeout rate 4.22 percentage points or more than 30% while excelling at inducing grounders. The righthanded sinkerballer had the best groundball and line drive (15.8%) rates in the NL last season. Amazingly, he also had the highest home run rate as a percentage of flyballs (17.1%). According to THT, "research has shown that about 11% to 12% of outfield flies are hit for home runs. For pitchers, significant variations from 11% are probably the result of 'luck'." Here's betting that Lowe's GB will remain fairly steady while his HR/FB rate regresses toward the league mean.
The biggest surprises in the northeast quadrant for me were Mark Hendrickson and Edwin Jackson. However, both had K and GB rates that were close to the league average. As such, I wouldn't classify either as a special pitcher. If anything, I would think of Jackson more along the lines of Daniel Cabrera, another power arm, than not. Both are blessed – or cursed as it may be – with that "p" word, as in potential.
SOUTHEAST QUADRANT (ABOVE-AVG K AND BELOW-AVG GB RATES)
Pitcher K/BF GB% Scott Kazmir 26.94% 43.15% Johan Santana 26.77% 38.02% Javier Vazquez 24.15% 39.77% Cole Hamels 23.82% 41.87% Chris Young 23.69% 29.15% Daisuke Matsuzaka 23.00% 38.39% Aaron Harang 23.00% 40.27% Oliver Perez 22.75% 32.79% Chad Billingsley 22.63% 41.04% Rich Hill 22.54% 36.01% John Maine 22.22% 36.96% Yovani Gallardo 21.67% 38.17% Justin Verlander 21.13% 41.12% James Shields 21.05% 43.38% Orlando Hernandez 21.05% 37.75% Ted Lilly 20.54% 33.67% Randy Wolf 20.52% 40.78% Wandy Rodriguez 20.20% 41.44% Chris Capuano 19.73% 42.95% Matt Cain 19.59% 39.44% Byung-Hyun Kim 19.04% 40.17% Ervin Santana 18.67% 35.64% Shaun Marcum 18.48% 40.17% Jason Bergmann 17.92% 33.43% Ben Sheets 17.91% 36.53% Brett Tomko 17.86% 41.01% Claudio Vargas 17.69% 33.79% John Danks 17.52% 34.76% Andrew Sonnanstine 17.51% 38.94% Brian Burres 17.17% 37.73% Jeremy Guthrie 17.01% 42.49% Bronson Arroyo 16.94% 35.28% Scott Baker 16.83% 34.64% Chuck James 16.79% 30.99% Jered Weaver 16.55% 35.65% David Bush 16.54% 43.36%
There are at least a dozen outstanding pitchers in this group, most notably those listed in the top half (or with K rates over 20%). Kazmir just missed the northeast quadrant although he had K and GB rates that were almost identical to Peavy, who just so happened to win the Triple Crown of pitching by leading the NL in ERA, wins, and strikeouts.
Young had the ninth-highest K/BF rate of all starting pitchers and was the only one with a GB% below 30. Despite being an extreme flyball pitcher, Young has benefited by pitching his home games at Petco Park, which tied with Busch Stadium for the second-lowest HR rate in the majors in 2007 (behind only RFK Stadium).
NORTHWEST QUADRANT (ABOVE-AVG GB AND BELOW-AVG K RATES)
Pitcher GB% K/BF Fausto Carmona 64.31% 15.59% Tim Hudson 61.96% 14.27% Sergio Mitre 59.73% 12.08% Chien-Ming Wang 58.45% 12.64% Aaron Cook 57.89% 8.74% Kameron Loe 56.33% 12.68% Lenny DiNardo 56.28% 10.63% Julian Tavarez 53.78% 12.75% Jake Westbrook 53.54% 14.35% Paul Maholm 53.25% 13.73% Roy Halladay 53.10% 14.99% Greg Maddux 51.48% 12.53% Zach Duke 50.62% 8.51% Jason Marquis 49.52% 12.88% Brad Thompson 49.46% 9.14% Justin Germano 49.19% 13.78% Joe Kennedy 48.93% 10.18% Brad Penny 48.72% 15.61% Matt Morris 48.48% 11.54% Kip Wells 48.21% 16.27% Sean Marshall 48.18% 15.02% Adam Wainwright 48.15% 15.42% Jesse Litsch 48.14% 10.46% Matt Albers 47.99% 13.98% Andy Pettitte 47.69% 15.39% Carlos Silva 47.54% 10.50% Chris Sampson 47.31% 9.77% Kyle Kendrick 47.06% 9.82% Joe Blanton 46.95% 14.74% Dontrelle Willis 46.44% 15.50% Kevin Millwood 46.42% 15.61% Vicente Padilla 45.69% 12.84% Joe Saunders 45.38% 14.59% Jeff Suppan 45.38% 12.40% Odalis Perez 45.36% 10.22% Noah Lowry 44.92% 12.54% Jose Contreras 44.89% 13.17% Nate Robertson 44.63% 15.24% Edgar Gonzalez 44.54% 14.19% Miguel Batista 44.07% 15.47% Chad Durbin 43.95% 11.76%
This is an interesting group of pitchers, ranging from the highly successful (Carmona, Tim Hudson, Chien-Ming Wang, Roy Halladay, and Brad Penny) to those fighting for a spot in a starting rotation or even the majors (Kameron Loe, Julian Tavarez, Jason Marquis, Brad Thompson, Justin Germano, Kip Wells, Sean Marshall, Matt Albers, Chris Sampson, Odalis Perez, Edgar Gonzalez, and Chad Durbin). There are also several hurlers who are still serviceable but have seen better days, such as Greg Maddux, Matt Morris, Andy Pettitte, and Kevin Millwood, as well as enigmas like Dontrelle Willis.
As a whole, they rank behind those in the NE quadrant and ahead of those in the SW quadrant. Opposite of the pitchers in the SE quadrant, the NW inhabitants succeed by inducing grounders and keeping the ball in the park, whereas their counterparts thrive on strikeouts.
SOUTHWEST QUADRANT (BELOW-AVG K AND GB RATES)
Pitcher K/BF GB% Micah B Owings 16.28% 37.45% Matt Belisle 16.21% 41.75% Josh Towers 16.20% 43.85% Scott Olsen 16.10% 37.65% Buddy Carlyle 16.02% 32.35% Curt Schilling 15.96% 37.27% Kyle Davies 15.76% 38.83% Anthony Reyes 15.61% 35.17% Jason Hirsh 15.53% 30.17% Tom Gorzelanny 15.45% 42.09% Barry Zito 15.41% 39.12% Jamie Moyer 15.34% 39.41% Kyle Lohse 14.72% 36.89% Jorge de la Rosa 13.92% 40.63% Mike Mussina 13.87% 41.91% Mark Buehrle 13.77% 43.23% Tim Wakefield 13.75% 38.90% Jarrod Washburn 13.59% 36.54% Adam Eaton 13.22% 39.29% Brandon McCarthy 12.85% 35.76% Josh Fogg 12.62% 40.04% Matthew Chico 12.58% 33.39% Jeff Weaver 12.18% 35.80% Woody Williams 12.12% 39.16% David Wells 11.82% 43.53% Braden Looper 11.66% 42.16% Brian Bannister 11.27% 40.83% Jon Garland 11.10% 39.44% Paul Byrd 10.54% 38.26% Tom Glavine 10.41% 41.75% Livan Hernandez 9.86% 38.45% Mike Maroth 9.29% 42.53% Mike Bacsik 8.65% 40.84% Steve Trachsel 7.98% 41.16%
Repeating what I said last year, "this is the quadrant that you want to avoid. It is inhabited by some of the worst starters in the game. If you fail to miss bats and don't keep the ball on the ground when it is put into play, you are going to run into trouble." There are two ways to survive (or perhaps semi-survive) in this quadrant: (1) being close to league average in both K and GB rates and (2) throwing strikes and maintaining a low walk rate. Matt Belisle, Josh Towers, and Tom Gorzelanny fit the first bill, while Belisle, Towers, Curt Schilling, Kyle Lohse, Mike Mussina, Mark Buehrle, Jeff Weaver, and David Wells would qualify under the second scenario. However, all of these types of pitchers live on the edge with very little margin for error.
When it comes to evaluating pitchers, I would rather know their strikeout and groundball rates than their ERA. Throw in walk rates and you have almost everything you need to know about a pitcher. Focusing on these components gives one a much more comprehensive understanding of a pitcher's upside and downside than looking at a single metric such as ERA.
Tomorrow: Categorizing Relievers by Strikeout and Groundball Rates.