One thing that has always confused me since I have become an adult who can think for himself is the whole “this guy is a number X pitcher”. What does it all really mean? Well, that depends on who you ask doesn’t it? It means a lot of different things for different people. Some people will use wins. Some will use ERA. Some will use FIP or XFIP. Some will use SIERRA. Others will use the pure stuff of a pitcher. At the end of it all, we are left confused with what any of it actually means.
Every few years I go back and look at things and try to break down what each position in the rotation actually looks like instead of what fiction suggests it should look like. So, to get started we need to understand that we need to alter reality somewhat to make this happen. Baseball talent is not evenly distributed. Not every team will have a #1 or a #2 pitcher (as we Reds fans know all too well during the Jimbo years). In this excersize we will assume that everyone is freely available and teams would pick in order, the best pitcher available to fill out their rotation, meaning every team will have one pitcher among the best thirty, one pitcher among the guys from 31-60, one guy from the 61-90 range, one guy from the 91-120 range and one guy from the 121-150 range. That equally distributes the talent across baseball and gives us a true determination of a #1, #2, #3, #4 and #5 pitcher.
So now we get into what kind of things we want to look at to determine that talent. Right off of the bat, I would eliminate ERA. Why? Well, a 3.50 ERA in GABP is outstanding. While a 3.50 ERA in Petco isn’t really that good. On its own, ERA doesn’t tell us much information. However, I do believe that ERA is very important to a starting pitcher, but we must be able to give it context of where guys are pitching at in order for it to be evaluated properly. For that reason, I look at Baseball-Reference.com’s stat of ERA+. Basically, it looks at a pitchers ERA and adjusts it for each park that he pitched in that season (home and away). 100 is league average and the higher the number, the better. I am also a fan of FIP (fielding independent pitching), which is scaled in a way to resemble ERA and as such, the lower the number, the better.xFIP is very similar to FIP, but it attempts to normalize the rate at which a pitcher gives up home runs based on the number of fly balls that they allow. In my opinion it is probably a little more accurate than FIP, but I do believe that some pitchers can suppress their HR rates on fly balls more than others even when accounting for parks they play in. If you want more detailed information on FIP and xFIP, you can check out Fangraphs glossary page, but expect to do some reading.
What I did was go through and gather data on every pitcher with 100 innings in a season from 2010-2012 and came out with a total of 437 pitchers. That leaves us with an average of 145 pitchers per season, or nearly enough to complete a 1-5 person rotation for every team. What I am going to do below is break down what each position in the rotation looks like if we were to sort them by different numbers (ERA+, FIP and xFIP) while also including different stats in those rates. I will also provide some examples of players who fell into that range.
Here is the data
|#1||121-256||140||2.6||7.8||3.3||193||Clayton Kershaw, Cliff Lee, Cole Hamels, Jared Weaver|
|#2||102-121||112||2.6||7.1||2.9||182||Chad Billingsly, Dan Haren, Mark Buehrle, Tim Hudson|
|#3||94-106||100||2.9||6.9||2.5||176||Aaron Harang, Edwin Jackson, Jamie Garcia, Phil Hughes|
|#4||83-94||89||2.9||6.4||2.3||157||Brandon Morrow, James McDonald, Jeff Francis, Luke Hochevar|
|#5||58-83||76||3.4||6.5||2.0||148||Brian Duensing, Chris Volstad, Francisco Liriano, Jake Arrieta|
|#1||2.20-3.46||3.12||2.5||8.3||3.6||195||Clayton Kershaw, Cliff Lee, Cole Hamels, David Price|
|#2||3.47-3.85||3.69||2.7||7.2||2.8||177||Brandon Morrow, Brian Duensing, Gio Gonzalez, Madison Bumgarner|
|#3||3.86-4.17||4.01||2.8||6.7||2.5||170||Bud Norris, Chris Capuano, Homer Bailey, Mark Buehrle|
|#4||4.17-4.62||4.37||3.0||6.5||2.2||165||Aaron Harang, Barry Zito, Francisco Liriano, Jeremy Hellickson|
|#5||4.63-6.55||5.00||3.2||5.8||1.9||150||AJ Burnett, Brad Bergesen, Freddy Garcia, Jake Arrieta|
|#1||2.56-3.60||3.24||2.5||8.6||3.7||193||CC Sabathia, Clayton Kershaw, Cliff Lee, Cole Hamels|
|#2||3.60-3.87||3.77||2.8||7.4||2.8||179||Brett Myers, Chad Billingsley, Edwin Jackson, Homer Bailey|
|#3||3.87-4.15||4.03||2.9||6.8||2.5||169||Brian Duensing, CJ Wilson, Jake Westbrook, Johan Santana|
|#4||4.15-4.47||4.34||2.9||6.0||2.2||165||Aaron Harang, Bronson Arroyo, Freddy Garcia, James McDonald|
|#5||4.47-5.57||4.78||3.3||5.6||1.7||150||Barry Zito, Bruce Chen, Jake Arrieta, Randy Wolf|
There are a few things that really stand out. First, there seems to be a rather large gap no matter how you look at it from a Number One to a Number Two. Mostly by simply looking at strikeouts and K/BB. It would seem that the first big identifier of a Number One starter is likely to be a high strikeout rate and a high K/BB rate. The average strikeout rate drops off at each step down. That makes plenty of sense. Strikeouts are nearly guaranteed outs. They leave fewer chances for “things to happen”. The next thing is that they also have the lowest walk rates and like the strikeout rates, they tend to get worse at each step down. There are exceptions to the rules, but generally speaking, the larger the difference you have in your strikeouts to walks, the better you are going to perform.
In the end, if you asked around between fans, managers, general managers and scouts, a lot of the examples listed above wouldn’t fit in the “ideal” spot that they fill. I believe this goes back to the history of baseball. Baseball is rich in history and the people love stats more than in any other sport. My belief is that the idea of “what a guy profiles as” goes back to when baseball had half as many teams. It is why scouts seem to think there are about 10 number ones (I will give them that there are probably 10 ACES, but that is an entirely different thing than a number one) and about 15 number twos. That doesn’t really work now, because there are 30 teams. But in 1950, that made sense. Since then, we have had announcers and writers tell us time and time again what scouts and front offices have said about what guys profile as and I think that those old ideas have simply just stuck. They unfortunately just aren’t based in the reality of todays game with the amount of teams there are and the distribution of the talent.