Aaron Brooks' Adjustments Through the Years

On Wednesday, right-hander Aaron Brooks made his first big-league start since September 13, 2019, with his only time in MLB since then being as a reliever in a short stint with the St. Louis Cardinals in 2022. In his return, Brooks tossed seven innings, gave up seven hits and three earned runs, walked one and struck out five in place of Paul Blackburn in the A's rotation. Not a bad showing against a lineup like the one that Houston boasts.

The A's dropped this one 3-0, but they couldn't have asked for much more from the 34-year-old that was signed to a minor-league deal a week before camp opened.

This is Brooks' third stint with the A's organization, and each of those stints has resulted in some time with the big-league club. He was originally acquired by Oakland along with Sean Manaea in the Ben Zobrist deal with Kansas City in 2015. He was acquired by the A's again in 2018 after the Milwaukee Brewers had designated him for assignment.

I thought it would be interesting to take a look at his pitch mix from each of those three stints with the club, because they are so spread out that they cover nine years of pitches being thrown, and they come every few years which is enough time to reinvent yourself in order to land another opportunity.

The first thing that stood out when looking at his Statcast data is that his fastball velocity is still there. In 2015 he was averaging 92.2 miles per hour on the four-seamer, and in 2018 it was at 91.9 mph. Last night in Houston it sat at 92.4. He's throwing just as hard at 34, if not a little harder, as he was at 25.

In 2015 he had under ten innings in the big leagues under his belt when he made his Oakland debut, so he was figuring some things out on the mound. He was relying on his four-seamer 41% of the time with an average velo of 92.2 mph, followed by his changeup (21.3%, 83.1 mph), sinker (19.1%, 91.8 mph), slider (14.5%, 85.7 mph), and curveball (4.2%, 77.7 mph). He ended up with a 6.71 ERA across 51 innings.

His next appearance in MLB also came with the A's, in 2018. He appeared in three games out of the bullpen and went 2 2/3 scoreless innings with Oakland that season. It was a super small sample size, but he ended up throwing his changeup the most this time around. The off-speed pitch was used 33.3% of the time, followed by his sinker (26.2%), four-seam (21.4%), curveball (9.5%), and slider (9.5%).

The following season he was back with the A's (until they placed him on waivers in July) and he had two noticeable differences in his arsenal. The first was that his sinker moved up to being his most-used offering at 28%. The second is that he scrapped the curveball and replaced it with a knuckle curve. He also starting mixing his pitches a little better, with four of his five offerings being used at least 20% of the time.

This started with the sinker, then was followed by the four-seamer (25.7%), slider (22.4%), and changeup (20.6%). The knuckle curve was used just 3.3% of the time.

Last night we saw yet another adjustment to his mix. The slider (36%) was the one he relied on against the Astros, which makes sense because every pitcher seemingly relies on a slider in some capacity these days. Behind the bender, he used his four-seamer (25%), changeup (20%), and sinker (18%).

These differences in pitch mix over the years show how pitching has changed over the last decade. The A's may have been a little behind in 2018-19 with having Brooks use the sinker as his primary pitch while teams on the cusp of analytics had starting moving towards the four-seam/slider combo, which still reigns supreme today. Hence Brooks using the slider as his primary pitch last night. These are the little adjustments that a pitcher has to make year-to-year in order to keep receiving opportunities.

With Brooks providing a solid outing and a light night for the bullpen, there's a chance he could stick in the rotation for the time being as the injuries among the starters continue to pile up.