Written by: John Storey
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Jake Arrieta was special from the moment he was selected in the fifth round of the 2007 draft. The contract he signed with the Orioles was a new record for a fifth-round draftee. The following year he helped the USA National Baseball Team collect a bronze medal in the 2008 summer Olympics. No doubt, an eventful start to his career.
Two years later, in 2010, Arrieta made his major league debut against the Yankees at Camden Yards. He’d pitch six pedestrian innings and go on to perform a little worse than league average through the rest of the season. It was a pretty typical rookie year. Especially for a starter. Especially for an Orioles team who only had one truly productive arm (Jeremy Guthrie).
2011 followed suit. It was essentially equally rocky. That’s not to say there wasn’t an improvement on Jake’s part. A slight uptick in slider, curveball and changeup velocity and usage helped Arrieta induce 4% less contact outside the zone and increase his swinging strike rate from 5.8% to 7.6%. He also increased his strikeout rate and traded a chunk of line drives for ground balls. However, there was little change in the results his efforts produced.
2012 brought more struggles. However, again, there were reasons for optimism. Jake Arrieta continued to improve his strikeout rate, now at 22% up from 17.8% in 2011. His walk rate also saw a new low, bottoming out at 7.1%. These improvements were masked by a magnified inability to prevent baserunners from scoring. He stranded just 57.3% of runners on base. His slash line with runners on base in 2012 read .296/.366/.484 – an OPS 23% higher than his baseline. That contrasted from the previous season where Arrieta allowed a .245 batting average, .347 on-base percentage, and .469 slugging percentage. His OPS with runners on base was just 6% higher than his 2011 baseline.
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This inflated his aggregate stats. His 2012 ERA was a lofty 6.20 – fourth highest among 142 pitchers with 100 innings pitched. His FIP was better, 4.05, and a particularly high home run to fly ball ratio further improved his xFIP to 3.65. There were distinct, tangible adjustments that had to be made, but Arrieta had the makings of a serviceable Major League starter.
2013 was a bit of a step back. Many of his numbers shifted back to their pre-2012 values. He tossed just four starts in April before being shuttled to AAA. He made one final start with the Orioles in June. It was enough for them to put more stock into his 2010 and ‘11 campaigns versus the promise he showed in 2012. And that was enough to justify moving him to Chicago, where the Cubs were perhaps more optimistic in Arrieta’s future.
Arrieta spent the month of July in AAA Iowa, where he pitched to generally good results. That prompted the Cubs to call him up for his first start in a Cubs uniform. Despite a six-inning, one-run outing, he made two more starts in Iowa before returning to Chicago to stay. He opened this stint up with a strong performance: Seven shutout innings with just two hits, two walks and seven strikeouts.
From August 16 through the end of the 2013 season Arrieta pitched to a 3.94 ERA, allowing a slash of .194/.298/.366. Averaging six and two-thirds innings across eight starts he struck out 6.9 batters per nine innings. As the calendar turned to 2014, Arrieta cemented his role atop the Cubs rotation. After that, Arrieta spent four elite and historic seasons in Chicago.
Jake’s success wasn’t a result of one singular adjustment. It was a critical combination of components that allowed him to thrive in Wrigley. I’m a big believer that a change of scenery can work wonders for a player, and I think that’s a contributing factor here. Arrieta was at crossroads when he was traded. Expecting a second child with his wife, Arriera was considering walking away from baseball. Chicago offered him a second chance. He took that opportunity and ran.
The Cubs also made some on-field adjustments with Arrieta’s approach. The first was a change in pitch usage. He changed the composition of fastballs he was throwing. He had been gradually decreasing the number of four-seam fastballs he threw before 2014, but in his first full season with the Cubs, he accelerated his sinker usage much more dramatically. While his sinker is inherently more effective, he began to effectively mix the two fastballs in Chicago, compounding their potential. That’s why, despite the two pitches’ remarkable similarity between 2010 and 2016, he was able to steadily increase his fastballs’ swing and miss rate.
It’s also worth noting his release point shifted outward. Based on a small sample of video, it looks like he spent more time on the third-base side or even the center of the rubber than he did earlier in his career. Thus, the change in release point wouldn’t have altered his pitches’ shapes, but him moving his release point further from the center of the strikezone likely helped Arrieta keep batters off his pitches a little longer.
Back to Arrieta’s fastball usage – which became critical to his success. He’s always required that his four-seam fastball back up his sinker – and not the other way around.
His four-seam fastball never was a great pitch, even before his decline in 2017. It had little to no break and not nearly enough spin to generate lift. It demanded some compliment. Enter the sinker. Living closer to the edges, the sinker is a pitch that doesn’t have to be a strike. But if it is, with reasonable break, certainly more than the four-seamer, it becomes more likely to induce weak contact.
He used his four-seam more exhaustively before joining the Cubs. And so Jake Arrieta exposed himself to that pitch’s weaknesses. Then, as a Cub, he increased his sinker usage, fighting batters with his best, while not eliminating the possibility of throwing the four-seam fastball for a strike. It thrived in a supporting role. The sinker flourished in the lead. But most importantly both pitches gained marginal effectiveness simply because the other was used in a more advantageous role.
Beginning in 2017, whether you choose to blame injuries or age for his decline, Jake hit a wall. Throughout four years of decline, three with the Phillies, the critical importance of balancing these pitches remained prominent. In 2017, Arrieta lost more than two miles per hour on his fastballs. This prompted him to rely almost entirely on his sinker, the pitch with better action. But with less velocity came less spin which allowed his fastballs to succumb to gravity.
Jake Arrieta has faced this problem for four years now. His arsenal doesn’t boast the same attributes it did his first time with the Cubs. Despite trying to adjust, the burdens that plague his four-seam fastball infect his sinker as well. If he’s fought through four years of subtle injuries, which is not an impossibility, he may have an opportunity to reprise some of his poise with the Cubs in 2021, especially if a lightened 2020 workload helps him to recover. However, if a lower 90s fastball is an inescapable trait of the soon to be 35-year-old, the likely scenario, he may merely be a relic of the past decade.
All data sourced from fangraphs.com, baseball-reference.com, brooksbaseball.net and baseballsavant.mlb.com.
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