I’ve always been fascinated with pitching. I’m not sure why, but I love to analyze pitching, including talking to scouts about it and making it one focus of my research and analysis. In past posts I’ve referred to my Starting Pitcher Rating System and Rankings. I developed this metric over the past two years in response to my dissatisfaction with the way in which existing stats measured a starting pitcher’s contribution to his team. Many traditional baseball stats tend to measure things in a vacuum, often missing the important interactions, such as the impact of the quality of the opponent on a player’s performance. Our traditional stats may be adequate (in some cases) to record and measure a player’s performance, but in their raw form are a poor indicator of his talent or skill. One reason is that traditional baseball stats typically measure the outcome of the batter—pitcher matchup, giving little consideration to the skills or attributes of the two parties. I’m not only interested in the outcomes, but also how the batter or pitcher got to that outcome—the process measures.
In developing my Starting Pitcher Rating System (SPR), I started with the definition of what baseball people value from a starting pitcher, with the ultimate goal of efficiently preventing runs. I looked at the things we ask a starting pitcher to do to accomplish that goal and categorized them as to whether they are focused on minimizing runs allowed, or getting outs efficiently.
It begins with outcome measures—the end result of the batter-pitcher matchup—that the pitcher controls: K-rate, BB-rate and HR-rate—the components of Fielding Independent Pitching (FIP). It also includes process measures–things over which the pitcher has some control that happen during the plate appearance: his swing and miss rate, the frequency with which he throws strikes, and his fastball velocity. Beyond these measures, there are four key metrics to capture the following aspects of a pitcher’s performance:
- It explicitly values groundballs over flyballs
- It values pitching deep into games, based on its affect on a team’s bullpen usage
- It gives starting pitchers credit for narrow platoon splits
- It adjusts for the quality of the opposition
Valuing Groundballs vs. Flyballs—While batting average on groundballs is slightly higher (.234) than average on flyballs (.219), slugging percentage on flyballs is significantly higher (.580 vs. .253 for groundballs). As a result, flyballs generate runs at a rate 2.5 times greater than groundballs. If an extreme groundball pitcher (e.g., Trevor Cahill of the Diamondbacks) and an extreme flyball pitcher (e.g., Colby Lewis of the Rangers), pitched equally effectively with the only difference being their batted ball tendencies, Lewis would yield 12% more runs and have a .030 higher OPS against, over the course of a season.
Pitching Deep into Games—In a recent study, I quantified the value of pitching deep into games, by analyzing the quality of relievers that typically pitch each relief inning–from innings 5 thru 9. The average OPS against relievers who pitch the 5th and 6th innings are .790 and .760, respectively. Relievers who cover the 8th and 9th innings have an OPS against of .690 and .670, respectively. The difference between starters who are “horses” and go deep into games vs. those who don’t is the the number of games they force their team’s bullpen to cover portions of the 5th, 6th, and 7th innings. Starting pitchers who fail to go deep into games, force the team to employ their weakest arms. Also, by adding bullpen innings, they reduce their manager’s flexibility in deploying the optimal reliever at key high leverage points during the game.
Narrow Platoon Splits—One of the key differentiators of a starting pitcher (versus a reliever) is the ability to pitch effectively to both righty and lefty hitters. Lefty relief specialist Clay Rapada of the Yankees is a good example of a pitcher who does not effectively pitch to both lefty and righty batters. He has a stellar career OPS against lefties of .502, but yields a 1.043 OPS vs. right-handed batters. Effective starting pitchers don’t have 500+ point differentials in their splits. The average difference in OPS splits for the top 140 starting pitchers (which includes teams’ 4th and 5th starters) is 109 points.
Quality of Opposition Adjustment—The array of teams a starting pitcher faces often gets overlooked when judging his performance. For example in 2011, CJ Wilson started 34 games. Fourteen of his starts were against teams in MLB’s lowest offensive quartile (as measured by OPS). Conversely, Toronto’s Ricky Romero had one of the toughest schedules of any starting pitcher, facing 1st and 2nd quartile opponents in nearly 70% of his starts. The SPR includes an adjustment to each starting pitcher’s stats to reflect the quality of the opponents he faced.
The top 20 starting pitchers for this season (through 9/2) are listed below:
According to the SPR, if the season ended on 9/2, King Felix would be the choice for the AL Cy Young award. The NL is much closer with RA Dickey having a slight lead over Cliff Lee, Clayton Kershaw and Cole Hamels. Undoubtedly some will be surprised at the ranking of both CC Sabathia and Cliff Lee in the top 5 starting pitchers this season. Regarding Sabathia, his last two starts (which are not included in this ranking) will clearly lower his rank and likely drop him out of the top 10. Cliff Lee is another story entirely. Despite his 4-7 record, it’s difficult to not give him accolades for another tremendous year on the mound. He excels at nearly everything we want a starting pitcher to do. He strikes out 6.5 times as many batters as he walks. He pounds the strike zone, throwing the highest percentage of strikes of any starting pitcher. In fact, he throws first pitch strikes to 71% of the batters he faces. His efficiency allows him to go deep into his starts. Only King Felix and Verlander have more innings pitched per start. I hold no illusions that Cliff Lee will win this year’s NL Cy Young, but it’s easy to make the case that he is not pitching poorly this season.
Another pitcher that scores consistently high in the SPR is James Shields. It’s probably a main reason I have come to regard Shields as one of the very best pitchers in baseball. On MLB Network I’ve raved about Shields as the leader of the best pitching staff in MLB. Last year he was ranked behind only Justin Verlander as the #2 pitcher in the AL. Despite having an “off year” this season, he ranks #13. There will be more on the SPR in future posts.