A commenter disagreed, saying, "I love Walter Johnson and think, of the two, he is the better pitcher; but, for me the greatest ever was Sandy Koufax. WJ had a far longer career than Koufax, but that 6 season period ('61-'66) which SK dominated was astonishing."
So I decided to compare Pedro and Koufax to see if this commenter was right.
As always, first we take a look at Baseball-Reference, and we come up with the following stats:
Three Cy Youngs (and four other top five finishes), two top five MVP finishes, one AL Pitching Triple Crown, 219 Wins, .687 Win Percentage, 409 Games Started, 46 Complete Games, 17 Shutouts, 2,827.1 Innings Pitched, 2.93 ERA, 154 ERA+, 1.054 WHIP, 3154 Ks, 760 BBs, 4.15 K/BB Ratio, 10.0 K/9 and an eight-time All-Star.
Three Cy Youngs (and one other top five finish), one MVP (and two other top five finishes), three MLB Pitching Triple Crowns, 165 Wins, .655 Win Percentage, 314 Games Started, 137 Complete Games, 40 Shutouts, 2,324.1 Innings Pitched, 2.76 ERA, 131 ERA+, 1.106 WHIP, 2396 Ks, 817 BBs, 2.93 K/BB Ratio, 9.3 K/9 Ratio and a six-time All-Star.
A quick glance at these stats shows Pedro leads in 10 of the categories (Wins, Win Percentage, Games Started, Innings Pitched, ERA+, WHIP, Ks, BBs, K/BB Ratio and K/9) and Sandy leads in four (MLB Pitching Triple Crowns, Complete Games, Shutouts and ERA). I didn't count Cy Youngs, MVPs or All-Star appearances (those awards have changed how they are handled over time).
Without looking deeper, Pedro is clearly the better pitcher. However, you need to delve into what the stats actually mean.
Let's start with the stats we can "throw away." In the article comparing Pedro to Walter Johnson, I discussed how wins and winning percentage are almost completely out of the pitcher's hands. Consequently, I don't really look at those stats when comparing players.
Also, the number of the complete games a pitcher throws and how many innings a pitcher pitches are more dependent on how bullpens are used, so those stats can be "tossed out"; they don't really tell you how great a pitcher was. After throwing these stats, Pedro now leads in six categories and Sandy leads in three.
As I discussed in my previous article, shutouts by themselves are not a good stat due to how bullpens are used today to maintain the lead in a close game instead of just letting the starter go the distance. What really matters is the percentage of shutouts a pitcher has out of his complete games.
By doing some simple calculations, we find that Pedro threw a shutout in 37 percent of his complete games, and Sandy threw a shutout in 29 percent of his. If given the chance, Pedro was more likely to have a shutout, and that now means Pedro leads in seven categories and Sandy leads in two.
The one category that is clearly in Koufax' favor is MLB Pitching Triple Crowns. His dominance over the league in 1963, 1965 and 1966 is one of the best stretches of dominance in baseball history. Pedro had one Pitching Triple Crown, but his was "only" for the American League. So Koufax will keep this category in his favor; however, I plan on covering who was actually more dominant a little bit later.
The final category that Koufax leads in is ERA. ERA is tricky because the era in which it occurred has to be accounted for. In Sandy's case, ERAs in all of baseball were lower across the board. How do we know this? Well, that's what ERA+ is for.
If we look at ERA+, we see that even though Pedro's ERA is higher, his ERA+ is much better in comparison. This means that relative to other pitchers' ERAs, his ERA was much better in comparison than Koufax' ERA was in comparison to others of his time. I'd rather have a pitcher with a higher ERA but better ERA+ than a pitcher with a lower ERA but lower ERA+.
The other stats that Pedro has a lead in (Ks, BBs, K/BB Ratio, K/9 and WHIP) further prove how much better of a pitcher pitcher Pedro was. He struck out more batters, walked fewer, had better control (K/BB ratio) and struck out more per inning than Koufax did. His WHIP also shows that he allowed fewer baserunners, and the opposing team can't score runs if it doesn't get men on base.
Now let's talk about dominance. This is what I believe is the main reason the commenter made the initial statement that started this article. Koufax' stretch of dominant seasons of 1962 through 1966 is among the best such periods of dominance in history. However, Pedro also has a similar period of dominance: 1997 through 2005 (minus injury-riddled 2001).
For this conversation, let's compare Koufax' '62-66 seasons to Pedro's best seasons during his dominant period (1997, 1998, 1999, 2000 and 2002).
Koufax' best WHIP was .875 in 1963; Pedro's was .737 in 2000. Koufax' best ERA+ was 190 in 1966; Pedro's was 291 in 2000. During the periods of dominance, Koufax had an ERA+ over 200 zero times, while Pedro had an ERA+ over 200 four times from 1997-2002. Koufax had a WHIP below 1.000 four times, Pedro five.
What this tells us is that even though Koufax is known for those years of dominance, Pedro had a similar period of dominance that was actually better.
The final thing to consider when comparing players is that you have to take their whole careers into account, not just a period of dominance, and this is where Pedro separates himself even further from Koufax.
They both started their careers at about the same age (19 for Koufax, 20 for Pedro); however, Pedro was a much better pitcher from the start, while Koufax' first six seasons were average—only had ERA+ over 110 one time, and WHIP was never lower than 1.284. Compare that to Pedro's first five seasons (his sixth season was the beginning of his dominant period), and you'll see that his ERA+ was never below 117 and his WHIP was never higher than 1.243.
If Koufax' career was only based on his last six seasons, he would have an argument as the best pitcher ever; however, when you account for his first six average/below average seasons, he drops in the all-time rankings. When you account for all of Pedro's career, he's clearly the best starting pitcher ever, and it's not even close.
What do you think? Do you agree? Do you want to make a case for someone else? Please leave a comment with your thoughts. Also, if you liked this breakdown and want to see me compare other players, please suggest them—players at the same position work best, but I'll compare any position to any position if needed (except pitchers, of course; they can only be compared to each other).