Five weeks ago, the question was asked here: Will the real David Peterson please stand up? And the six games since that post, Peterson has gone 3-1 with a 2.88 ERA in 34.1 IP. The last four starts have all been good. And while he’s still out-pitching his peripherals, there’s enough there to make one hope that he can continue this run for the remainder of the season.
One of the nice things about the ERA estimator FIP is that it can tell you fairly quickly if a pitcher is having luck. We can’t say definitively that at such-and-such point, FIP becomes reliable. But if there’s a large difference between a pitcher’s FIP and ERA at the 50-IP mark, you probably want to become alarmed if the FIP is noticeably higher than the ERA.
Last year, in 111 IP, Peterson had a 5.03 ERA and a 4.34 FIP. Which means that Peterson’s peripherals painted a better overall picture of his performance in 2023 than his ERA. We would expect Peterson’s ERA the following year (this season) to be lower than his 2023 ERA. Now, it doesn’t mean that we would expect a 4.34 ERA. Instead, we would expect his ERA to move in the direction of his FIP.
And, indeed, Peterson has had a lower ERA this season. The issue is that right now his ERA is 3.00 and his FIP is 4.27, in 78 IP. We know that, at some point, regression is coming. The issue is that we don’t know if it’s coming this start later today, or in four weeks or next year.
For his MLB career, in 411 IP, Peterson has a 4.23 ERA and a 4.24 FIP. Now, it doesn’t always work out this nicely. But in the long run, these measures should be fairly close.
This is Peterson’s fifth year in the majors. In that time span, his ERAs have ranged from 3.00-5.54 – a fairly wide span. But it’s been much narrower with his FIP, which has seen a spread of 3.64-4.78 in the same time span.
With his 95 ERA+, we can peg Peterson as an SP4. But as he’s never had more than last year’s 21 starts and 111 IP, we can and have seen wild fluctuations in his performance. Right now, based on ERA and compared to all 150 starters who’ve pitched at least 50 innings, Peterson is pitching at the level of an SP1.
It’s among the possibilities that Peterson will exhibit better peripherals moving forward. The article on 7/17 noted that he had a 4.54 FIP and he’s cut that 27 points in his last six starts. Hopefully, that’s a trend that will continue the rest of this season and beyond.
Conventional wisdom used to be that it took lefties longer to get established and thrive than it did righties. And maybe we can hang our hat on that with Peterson, that he’s getting established here in his age-28 season and he’ll begin to thrive next year. In his age-28 season, Randy Johnson was 12-14 with a 105 ERA+. The next year, Johnson won 19 games and had a 135 ERA+, beginning a streak of 10 straight seasons with an ERA+ of 135 or greater.
No one should expect that type of growth from Peterson; it’s merely an example of a lefty taking longer to put it all together. Maybe Peterson can start a streak of five consecutive years with a 115 ERA+. It’s among the possibilities.
But right now, we can’t be worried about what Peterson will do next year and beyond. We just need him to give a strong outing today on the road versus a team the Mets are chasing in the Wild Card race.
As I put in FanGraphs all pitchers above 70 innings to make the scope as narrow as possible (they didn’t offer 75 innings) in FIP Peterson is 89/145. And Severino is 90th. If it was ERA, as you propose, it is 13th. But here is the problem: the xERA, FIP, xFIP all are cruel to pitchers with high walks because those guys usually get bombed. But, Sid Fernandez always had high walks, but low hits. Peterson is the same. There have been others, say Doug Sisk, say Mitch Williams. I’m glad the guy is doing well and as long as he stay out of the middle of the zone, he will be fine.
Consistently, when Peterson’s HR/9 is below 1.00, his ERA is below 4. That’s because he has always walked alot of batters and the expected stats take an average HR/9, which doesn’t explain Peterson’s pitching.
In comparison, most other pitchers with low walks have pristine ERA’s, all except Ross Stripling who has a low walks total and a low HR total but still has a 5.40 ERA. That why he was still in demand at the trade deadline, but he is complicated as he has a low LOB% and high BABIP, meaning he has also been unlucky, but with a 5.34 K/9%, he is also fairly easy to hit. Plus, he has a low GB% while Peterson’s is 53.9%.
Sorry, Stripling’s GB% is 39%, just for comparison.
My point is Peterson knows himself and what he needs to do. Expecting Inglesias to be at 3B tonight, LOL.
Mets have invested much time , attention and hope in Peterson. I think he is on the right track to remain consistent. He may finish around 11- 3 or something like that, double digit wins and a sub 3.00 ERA, establishing himself with Senga and hopefully both Manaea and Severino staying next year as well to form a decent rotation. May the best rookie win the number 5 spot, maybe Scott, maybe Sprout, maybe even Butto changing roles. Mets have waited long and hard for both pitchers Peterson and Megill. Peterson looks like the one that rewards them. Megill ? Nope, not as starter. Maybe a future BP arm.
I’d like to place an order for tonight’s game, for Mr. Peterson – 7 IP, 2 R. Quite reasonable, not too greedy.
Peterson also ranks 92 /150 and 112/150 WHIP with Brian’s criteria. That would be SP4 and that is what he is. His ERA is smoke and mirrors. That isn’t a put down. Peterson is a MLB starter and should be in the Mets rotation plans in 2025.
He has certainly stepped up this year and turned his season around. Except for Quintana, their starters have been strong. Peterson should be a mainstay going forward.