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Jake Arrieta

His career started slowly. A trade led to his success.

Jake Arrieta
Jake Arrieta
Photo by Michael Owens/Getty Images

Jake Arrieta’s career started slowly.

Brutus: “There is a tide in the affairs of men, which, taken at the flood, leads on to fortune; Omitted, all the voyage of their life is bound in shallows and in miseries.” — Shakespeare’s Julius Caesar

Jake Arrieta played for the Orioles. In his first two seasons they finished last in their Division. In his first three seasons, his ERA+ was below average and getting worse (89, 83, and 68). Halfway through his fourth season he was 27 years old and his ERA+ was 57. He missed the tide.

Perhaps Brutus overlooked something important when he looked at the tide in the affairs of men. A person who keeps swimming, when their life is bound in the shallows, can experience a riptide leading to an ocean of good fortune.

For Jake Arrieta, that riptide happened on 2 July, 2013. The Orioles traded him to the Cubs. In his first 12 months as a Cub something amazing happened.

“Whether Arrieta can continue pitching this well for the Cubs remains to be seen (with just 64.2 innings pitched under his belt in 2014, the small sample size caveat still applies here). Even so, Arrieta appears to have turned some type of corner, with improved command buttressing what was already an impressive arsenal.” — Alex Skillin, 1 July 2014

Before the 2015 season started, he added another layer of amazing. He greatly reduced use of his 4-seam fastball (19.9% to 7.5%) while increasing use of his sinker fastball (27.6% to 43.0%). That season, it’s no coincidence that he won the Cy Young.

In 2016 he was the winning pitcher in games 2 and 6 in the World Series, which the Cubs won. In the World Series his 2.38 ERA was awesome. Articles (here and here) considered his chances to reach the Hall of Fame. Data from FanGraphs and Baseball Reference.

His career can be seen in a graph.

The following graph is a visual representation of his career to date. It shows teams, his ERA+ and SO/BB. It annotates career highlights.

Jake Arrieta. Data from Baseball Reference.

He became a free agent and he signed with the Phillies.

With the Phillies, his ERA+ dropped to about average. Although part of his decline was likely due to aging, injuries had an impact. In 2019, he had a bone spur in his elbow. In the shortened 2020 season he had a hamstring injury.

Despite the possibility that injuries explain his lesser results with the Phillies, my view is that an essential ingredient in Jake Arrieta’s extraordinary success was playing for the Cubs. In 2021, it is fortunate that he returned to the Cubs.

This season he signed with the Cubs.

He made significant changes in his pitching. He mainly replaced his changeup (fell from 17% to 6% of pitches) with his curve (increased from 7% to 16% of pitches). One reason for the change could be that his whiff rate for the curve increased from 31% to 40%. He improved his sinker (wOBA improved from .470 to 426); that pitch was remarkably better at the start of the season (wOBA of .339 from April 1-29). Data from Baseball Savant.

Most of his pitches (78%) are sinkers and sliders. He had three challenging games (30 April, 4 June, and 6 July). Excluding those games, let’s look at wOBA and K% for his sinkers and sliders.

  • Results with his slider were great in April and June, and much worse in May.
  • Results with his sinker were better than last season; Sinkers were best in April, and slightly declined in May and again in June.
Jake Arrieta 2021. Data from Baseball Savant.

In my view, two of his three challenging games were due to injury. On 7 July he was put on the 10 day IL with a strained hamstring retroactive to his 6 July start. Manager David Ross said that Arrieta has been pushing through injury that can be traced back to late May (explaining the 4 June challenging start).

This season, why were results better for Jake Arrieta’s sinker? Part of the answer is location.

“The game now features more swings built to generate launch angle against low pitches, which has been terrible for Arrieta’s heavy-sinker repertoire.” — Brendan Miller, February 2021 in this article

“As smart as a lot of these analytical teams are…Taking guys that throw sinkers and transitioning them to a guy that throws four-seamers up. It’s happened all around baseball and it’s foolish. — Jake Arrieta 2020

The Cubs took a different approach, an approach that appealed to Arrieta (per Brendan Miller). Instead of throwing 4-seam fastballs up in the zone, they encouraged him to throw more sinkers up in the zone. This season, Jake Arrieta threw 0.1% 4-seamers while increasing sinkers from 51.9% to 54.2%. Data from FanGraphs.

The last two weeks were disappointing for the Cubs because they fell from first place in their Division on 24 June to 9.5 games back on 8 July. When Jake Arrieta returns from the IL, he will likely be an above average starter who can make an impact.

A smart move could be to trade him for prospects. My view is that trading him would be a mistake because, as I wrote previously, an essential ingredient in his success is playing for the Cubs.

“Down and away is and will always be good.” — Jake Arrietta