Minor introduction about myself, if you don’t want to read just skip to the next paragraph, I’ve read this site for a long time (since approximately 2007) but never bothered commenting since I had plenty of friends and family to discuss the Cubs with. However, now I live in Korea and therefore do not have a lot of people to discuss this stuff with and, so, here I am. I researched and wrote this piece because after a Travis Wood start towards the end of the season Al said something to the effect that Wood, like Ted Lilly, can still be a piece of the rotation in the future because left handed pitchers develop later than their right handed counterparts to which I believe epsilon asked for numbers to back up this belief. Al didn't have them, but as just about anyone who has watched baseball for a long time or been around people who follow and play baseball this is a pretty common belief (or at least one that is repeated every now and then). So I decided to do some research and here are my findings.
Generally speaking, left handed pitchers (and players for that matter) have more stereotypes about them like; left handed pitchers throw more breaking balls, left handed hitters can’t hit left handed pitchers, crossing sports, left handed quarterbacks are tougher to catch, and left handed pitchers develop later than right handed ones. Ted Lilly is regarded as a standard “Lefties develop later” pitcher, looking at some of his stats we can see that this is fairly well founded. His first full season (appearing in 20+ games or having a 100 or more innings) didn't occur until he was 25 (fairly standard), the first season he posted a WAR reasonably above 1 wasn't until he was 27 (again not that late) where he posted a WAR of 3, however if you look at his other stats that year ERA of 4.34, and a FIP of 4.19 (just below average) you see that his numbers still weren't stellar. The following year his numbers improved to a WAR of 3.3, an ERA of 4.06, his FIP took a hit though at 4.5 and that can’t be attributed to luck with a BABIP of .261. This all fell apart the following year when he was 29 and posted .7 WAR, 5.56 ERA, 5.32 FIP. So as the stereotype, along with the evidence shows, he hadn't developed into a consistent starter yet even though being 29. His first stretch of consistency was from 2006 (30) to 2010 (34) where he posted a WAR of 2.3, 3.6, 2.8, 3.7, and 2 respectively the rest of his numbers adjusted accordingly with his WAR with the obvious high point being 2009, WAR of 3.7, ERA of 3.1, FIP of 3.65, some luck was involved in that season with a .261 BABIP. However, he fits the mold of the stereotypical left handed pitchers that develops later. My goal is to see if this is an actual trend or if it is merely an old myth. Looking at a list of 113 pitchers I am going to attempt to determine if there is a major statistical gap between when right handed and left handed players “develop”.
Obviously the term “develop” is a subjective one so I’m basically going to use what is generally accepted for Ted Lilly, as in multiple years in a row of consistent solid or above level play by said player (i.e. a WAR of 2 or more, but will not be limited exclusively to this stat). I will also look at what age they came into the league and when they were given significant starting time (when the manager felt that the player was ready to face major league opponents for a full season). The list I used to find these names was pitchers with 200 or more wins. I used this because, honestly, it was the easiest list I could find that had a large sample of players both right and left that didn't involve me alphabetically going through every baseball player and analyzing their stats. I only added two left handers, Ted Lilly and Sandy Koufax, since the former was what started this debate and the latter is regarded as one of the greatest pitchers of all time and has said to have a similar progression to his career. After starting the list I found some benefits to this in that I’m using players from every time period (save the last 5 – 10 seasons) and I’m using a large number from the early days of baseball where this notion of left handed pitchers developing later probably came from. The list has 29 lefties and 84 righties or a 25/75 split and that is roughly the predicted percentage of the left handed world population (according to Wikipedia anyway).
Using the stats I compiled I attempted to figure out what age all of these players became consistent (i.e. developed major leaguers). Basically, I looked at their WAR and tried to find where they put together three or more years of consistent 2+ ball. At this point I would look at their other stats to determine if the year where they fell below 2 was due to inconsistency, a bad season among an otherwise upward trend or purely because they were just unlucky. For example I put Chuck Finley at 26 for when he became a consistent pitcher, he threw 4 seasons of 2 + win ball with a respectable FIP (high point being 3.3) and a BABIP that never indicated him relying purely on luck. After this he had one poor season of 1.6 WAR with a pretty bad 4.58 FIP. However, after this season he continued on his a path of his previous seasons progression, indicating that it was just a poor season. As compared, for example, to Kevin Brown who in his first full season of pitching threw for a strong 3.6 WAR with an above average FIP 3.52 (benefiting from a .257 BABIP) the next season he regressed and bottomed out with a 1.8 WAR at age 26. After this season he bounced back and consistently pitched at an average to above average level that continued for the majority of his career. Therefore, I felt the earlier season was more a aberration of him being a new pitcher in the league and that he didn't really develop a quality level of pitching until the year after his 1.8 WAR season.
So after going through all of the stats I compiled the list of players that included; the age they came into the majors, at what age they started pitching on a regular basis, and what age they started pitching average or better (i.e. 2+ WAR) consistently. So according to what I've put together the average age of right handed pitchers goes; 22.11, 23.26, and 24.78 respectively, while left handed pitchers came in at; 22.03, 23.34, and 25.17 respectively. That means that the difference in age when it comes to how old these pitchers were when they became average or better players was practically the same (about a half year difference). Even the difference in how many years from when the pitcher first appears in the majors to when they become a consistent quality player are only separate by half a year. Right handed pitchers have taken, on average, 2.68 years from call up while left handed pitchers taken, on average, 3.14 years, almost exactly the same difference to the difference age development. So then, why is there this notion that left handed pitchers develop so much later than right handed pitchers?
I can’t honestly act like I know why this stereotype follows left handed pitchers. Looking at my stats the one tendency that I do notice is that when baseball was beginning (late 1800s early 1900s) more right handed pitchers started pitching at an average to above average level earlier, but this is also due to the fact that there are more right handed pitchers than left handed ones (I have none in the late 1800s). That can possibly be the crux of the issue, since there’s more right handed pitchers it’s easier to see their development on a case by case basis as compared to left handed pitchers where a manager may only have 2 or 3 back then and he would see one develop later and automatically assume that most left handed pitchers follow this developmental path. This is purely conjecture, I’m not saying that this is the definitive reason I’m just pointing out a possibility as to why there is a belief that left handed pitchers develop later than right handed pitchers.
Now I understand that this a small sample size to be making a judgment call from and I’m not claiming this to be anything more than an amateur doing some research, but going from this sample of 114 players ranging through the entire history of baseball you’d believe that there would be at least a wider discrepancy than .5 years. The other argument I can see against these findings is the players I used for this research, almost all players with 200 wins or more, are potential hall of fame players or at the least in the hall of the very good. This is one that I don’t have much of a rebuttal for except that A) all of those players aren't hall of famers and some of them I’d have a tough time saying they’re very good and B) plenty of the players, 11 of 114 or just about 10% (9.6 to be exact), I claimed developed at the age 30 or later. Not having the exact numbers in front of me I’d be surprised to see a percentage much higher than that among average players. So basically what I’m claiming here is that although the number of players I’m using here is somewhat small and biased towards the elite, the percentages don’t seem to be far off from what you could expect if you used a wider range of “average” players.
So, like the idea that left handed pitchers throw slower and therefore have to rely on more breaking balls, the idea that left handed pitchers develop later is pretty much just a myth. The source for all of my statistics is fangraphs.com and I would like to post the spread sheets showing the stats and how I came up with these numbers, but unfortunately I can't figure out how to do that, so yeah, sorry. If you have any questions, comments, arguments, disagreements on what age players “developed”, or errors I made by all means have at it.
Thanks for reading.
By the way, my responses might be delayed (I’m 15 hours ahead of CST).