Breaking down New York Mets starter David Peterson

For whatever reason thus far this season, the Dodgers have really struggled against left-handed pitching. They’ve hit .185/.324/.404 with 44 strikeouts in 179 plate appearances (24.6 percent).

Part of this can be attributed to the fact that Freddie Freeman, a left-handed hitter, is much worse against lefties in his career than righties, though still above average. But a lineup that still features the likes of Mookie Betts, J.D. Martinez and, for a time, Will Smith should be able to more than hold their own against southpaws.

Unfortunately for the Dodgers though they will be facing one on Monday in Mets starter David Peterson. Down below we are going to evaluate what the 27-year-old brings to the table.

Will include batted ball profiles next week. Unfortunately, there is not enough 2023 data in that category yet to have it support any claims.

Pitch #1: Four-seam, 2023 usage rate - 30.6 percent

2023 stats - Average velo - 93.3 MPH - Spin rate - 2,170 RPM - vertical movement - 16.9 inches - horizontal movement - 0.0 inches

There have been some interesting changes in the numbers against Peterson’s four seamer early in the season. The first being the ground ball percentage on the pitch has gone from 43.2 percent in 2022 to 66.7 percent this season with the launch angle dipping from 10 degrees to -1. Additionally, his four seamer has been less accurate this season as its in-zone percentage has dropped from 56.1 percent in 2022 to 38.3 percent in 2023. When thrown in the zone though, hitters are swinging at it at an increasingly higher rate jumping from 65.2 percent to 74.2 percent. I’m not sure if this is an overall adjustment from hitters who are hunting his four seamer early and often or if this is a pure coincidence but look for the likes of Mookie Betts to hunt this pitch all game.

Pitch #2: Slider, 2023 usage rate - 24.9 percent

2023 stats - Average velo - 85.8 MPH - Spin rate - 2,454 RPM - vertical movement - 37.3 inches - horizontal movement - 3.0 inches

Despite it being less effective this year, the slider is Peterson’s best pitch. It carried a whiff rate of 47.9 percent in 2022 and 42.4 percent thus far this season. Over the past two seasons as well Peterson has produced chase rates of 41.1 percent and 35.1 percent with it. Notably, Peterson’s slider is his most used pitch against left-handed batter, with a usage rate of 40.7 percent and 36.1 percent over the past two seasons. Against righties though it takes a big dip at 26 and 19.8 percent respectively. As a result, the few left-handed hitters in the Dodgers' lineup on Monday should expect to see the slider early and often.

Pitch #3: Changeup, 2023 usage rate - 20.4 percent

2023 stats - Average velo - 86 MPH - Spin rate - 1,629 RPM - vertical movement - 28.9 inches - horizontal movement - 16.3 inches

Behind his slider, this is in my opinion Peterson’s second-best pitch, which he uses nearly exclusively against right-handed hitters. Over the past two seasons he has thrown it 345 times to righties compared to just 16 to lefties. This is a pitch that Peterson does throw largely out of the strike zone as in 2022 the out of zone percentage on it was 69.1, the highest amongst all of his pitches. Surprisingly though, despite being thrown out of the zone so frequently last season it only generated a chase rate of 20.8 percent.

Pitch #4: Sinker, 2023 usage rate - 17 percent

2023 stats - Average velo - 92.9 MPH - Spin rate - 2,195 RPM - vertical movement - 25.2 inches (4.4 inches above average - horizontal movement - 0.0 inches

Honestly, I can’t say I really understand the purpose of his sinker. It does give him a pitch that breaks in on lefties, but he only threw it 12.6 percent of the time against them last season. Left handers did hit the pitch quite well last season as well with an xSLG of .499 and xWOBA of .372. Righties had similar success as well against it posting an xSLG right above .500 and xWOBA a hair under .400. Perhaps the most surprising part of his 2022 to 2023 adjustment is the usage rate on the pitch increase 5.3 percent this season despite its limited success.

Did not include his curveball which he threw 5 percent of the time last season and 7.2 percent thus far this season.

Key matchup to watch: Mookie Betts

Betts only has two career at bats against Peterson, so there isn’t a whole lot to go off in that category. Despite being about even in terms of lefty/righty splits over his career, Betts had a significant gulf between the two splits last season. He had a .983 OPS vs lefties and a .832 OPS against righties, meaning this is a matchup Betts has to dominate. Peterson’s two most-used pitches this season are ones that Betts has dominated in the past. His run value per 100 pitches faced against four-seamers last year was 1.9 and against sliders it was 0.9. If the Dodgers are going to flip the early season script against lefties, it is going to start with Betts having a big game, which I think he will.

Prediction: Peterson pitches five innings, allows three earned runs and strikes out five batters.