Jake Arrieta appears to be on the downside of his career. While we can’t rule out a resurgence, his ERA last year was 4.64, and he is 34 years old.
If Arrieta’s career is nearing the end, he will be remembered as an accomplished pitcher, but not a great one. From 2014 to 2017, he was excellent, peaking with his Cy Young Award in 2015. Otherwise, his career has been unremarkable. He is probably one of the 500 greatest pitchers of all time; perhaps there is an argument to put him in the top 300. Farther than that, we cannot go.
But for one calendar year – from June 21, 2015 to June 20, 2016 – Jake Arrieta was the greatest pitcher who ever lived.
| G | W-L | IP | H | R | ER | BB | SO | HR | ERA | BA | OBP | SLG | OPS |
| 34 | 27-2 | 240 | 133 | 36 | 32 | 58 | 248 | 5 | 1.20 | .159 | .220 | .221 | .441 |
Let’s analyze this as if it were a single season, and compare it to the greatest pitching seasons of all time.
The W-L record of 27-2 would be the greatest of all time for a starting pitcher. The only starting pitchers in history (not counting Al Spalding in 1875) who won 90% of their decisions were both in 1995 – Greg Maddux (19-2) and Randy Johnson (18-2).
The ERA of 1.20 would be the second lowest in the live ball era, second only to Gibson’s 1.12 in 1968. Arrieta’s is more valuable because he pitched in a much higher run-scoring context.
No pitcher with >100 IP has ever allowed fewer than 5 hits per 9 innings over a full season. Arrieta’s was 4.99.
Only one starting pitcher in the live ball era has had a WHIP (W + H/IP) of less than 0.8 – Pedro Martinez in 2000 with a 0.737. Arrieta’s was 0.796.
Only 6 pitchers since World War II have pitched over 200 innings and allowed 5 or fewer HRs. Arrieta allowed 5.
Arrieta’s OPS allowed of .441 would be by far the lowest all-time for a pitcher with at least 85 innings pitched. There are only 4 starting pitcher seasons (>180 IP) with an OPS allowed of less than .500:
- Tiant 1968 (.495)
- Maddux 1995 (.482)
- Martinez 2000 (.473)
- Gibson 1968 (.469)
The lowest slugging % allowed in a season with at least 150 IP in the live ball era is Gibson in 1968 with .236. Arrieta’s was .221.
Maybe, just maybe, Pedro in 2000 was better, given that he pitched in a much higher run-scoring context. Otherwise, I submit to you that Arrieta’s “season” is the greatest pitching season of all time.