Scouting Aaron Brooks

How do you face one of the best in the KBO?

Major League Baseball has finally made its return in the United States, but in a country with COVID-19 under control, baseball has been playing since May. The Korean Baseball Organization (KBO) is about halfway through their 144 game season and a former MLBer has been one of the best pitchers in the league.

Here’s how he’s done it and what you can expect from Aaron Brooks when he’s on the mound for the Kia Tigers.

Han Myung-Gu / Getty Images Sport / Getty

Aaron Brooks is a 30-year-old RHP who was drafted by the Kansas City Royals in 2011 in the 9th-round out of California State San Bernardino. Throughout his MLB career, he bounced around the league, pitching for the Royals, the Athletics, and the Orioles before jumping over to the KBO following the 2019 season to sign with the Kia Tigers. Since joining Kia, Brooks has been phenomenal, anchoring their pitching staff.

As I’ve been watching and charting KBO games, I’ve gotten to see Aaron Brooks pitch three times, including his last two starts. I wrote about the first start against the Lotte Giants here and again about his July 17th start against the Doosan Bears here. Based off of these two starts and his most recent outing against the Samsung Lions, I’m taking a deep dive into Brooks as a pitcher using the pitch-by-pitch data that I’ve charted, as well as pulling in available stats from places like FanGraphs and MyKBO. So, without further ado, lets jump in and explore what makes Aaron Brooks successful.

Aaron Brooks stats and KBO ranking as of 7/26

Brooks is one of the best pitchers in the KBO, with his ERA of 2.54 ranking 5th in the league and his FIP of 3.08 ranking 3rd. His biggest strength is his amazing control of the strike zone and ability to throw strikes; Brooks has thrown a strike on 72% of the pitches I’ve seen him throw and a first-pitch strike a whopping 75% of the time, which would have beaten Max Scherzer’s MLB-leading 2019 mark of 70.3%. That’s reflected in his low BB% of 5.1% that ranks 4th in the KBO, which compensates for his average K% of 20.3% to result in the 6th best K-BB% of 15.3%.

The next best thing that Aaron Brooks does in keep the ball on the ground and limit hard contact. Brooks has a phenomenal 33/12 groundout-to-flyout ratio in games I’ve seen and has only allowed 0.30 HR/9, a mark that ranks second in the KBO. Combined with his KBO low hard-hit rate of just 11.5%, it’s clear that limiting hard contact is a priority for Brooks. He struggled to do so while pitching in the MLB, allowing a hard-hit rate of 36.8% in his 110 IP with the Orioles in 2019, an Average Exit Velocity in the 21st-percentile and xwOBA in the 14th-percentile, according to Baseball Savant.

I think that limiting flyballs and hard contact was a conscious goal of Brooks and he tailored his pitch arsenal to help him accomplish that.

Velocity numbers for Aaron Brooks in 2020 with the Kia Tigers

Aaron Brooks has thrown four different pitches that I’ve seen, a sinker, slider, changeup, and an occasional curveball. He’s thrown his sinker about 51% of the time and mostly cut out his four seam-fastball, a pretty big change considering he threw his sinker 28% of the time and his four-seam 25% of the time in 2019. His sinker velocity has also ticked up an mph, up to 92.8 mph from the 91.8 mph he was throwing back in 2019 with the Orioles and Athletics.

Brooks backs up his fastball with his slider and changeup. He throws his slider around 24% of the time at about 86 mph, although it’s primary use is against RHH. His changeup, thrown 20% of the time and coming in around 85 mph, is Brooks’ best pitch and go-to weapon against LHH. He rarely throws his curveball, only using it 5% of the time this year after throwing it just 3.3% of the time in 2019. His curveball is more of a change of pace pitch than any sort of regular weapon.

The biggest change Brooks has made is turning almost exclusively to his sinker. I think this move has benefited him, considering the ways that his changeup and slider move relative to his sinker, which we’ll dive into more later.

Location of Aaron Brooks pitches

Overall, Brooks’ primary approach is applicable to both right-handed hitters and left-handed hitters. He throws a steady diet of sinkers up and in the strike zone while pairing it with his changeup or slider down and away.

But an important part of analyzing an opposing pitcher is knowing what pitch he likes to through in different situations.

A visual representation of what pitch Aaron Brooks throws in each count

For each potential pitch count, I’ve pulled the number of each pitch Brooks has thrown and compiled it into this table, with green filled boxes indicating he’s likely to throw the pitch in question, red indicating that he likely won’t throw the pitch and yellow indicating some uncertainty. We’ll examine his pitch tendencies by LHH vs RHH a little more in-depth soon, but let’s take a look at his overall approach.

Aaron Brooks isn’t the most extreme fastball-heavy pitcher in the KBO (that’d likely be Chris Flexen), but his sinker is still his most used pitch (also, an interesting note is that Aaron Brooks, over the 313 pitches that I’ve charted him throwing, has not reached a 3–0 count versus any batters, another testament to his command and control). His sinker is his go-ahead pitch against hitters and the pitch he turns to when he needs a strike. He uses his changeup and slider later in the count, with his slider frequently being used in two-strike counts and his changeup being used when’s behind or even in the count.

Brooks has been excellent overall but has been great against RHH, holding them to a 0.216 batting average on the season, while LHH have hit 0.286 against him. However, he’s gotten more strikeouts (38) against lefties than he has against righties (34). A big part of that has to do with how he uses his pitches against opponents, something we’re about to dive more into.


Stats for Aaron Brooks’ sinker, broken down by batter handedness

Aaron Brooks has turned into a sinker-heavy pitcher with the Tigers. It’s his most used pitch, throwing it 56% of the time against RHH and 48% of the time versus LHH. It’s an incredibly reliable pitch for him, and the pitch that he can throw for a strike almost whenever he wants it. He uses his sinker as a go-ahead pitch, throwing it 53% of the time in 0–0 counts, 50% of the time in 2–0 counts, and 67% of the time in 3–2 counts.

Locations for Aaron Brooks’ sinker, broken down by RHH vs LHH

At about 93 mph, with a wicked cut towards Brooks’ arm-side, his sinker is already a really tough pitch to hit. Based off of that movement profile, Brooks uses his sinker differently against RHH than he does against LHH. It’s his go-ahead pitch against righties, with just an 11% whiff rate. As you can see on his plotted sinker locations, he throws his sinker inside against RHH, which really helps induce those groundballs and that weak contact that have been crucial to Brooks’ success.

Against LHH, with that sharp cut back towards Brooks’ arm-side, his sinker is a heavier swing-and-miss pitch, with a 23% whiff rate. Brooks accomplishes this by throwing the sinker up and ramping the velocity up to the 94–95 mph range when he’s hunting a swing-and-miss. In addition, he pairs it really well with his changeup and slider, which only boosts the deception factor. He avoids throwing it in the middle of the plate, for the most part, effectively locating for a strike on the inside edge of the plate, for a whiff up in the zone, or for a groundball away from LHH.

Aaron Brooks’ sinker, changeup, and sinker’s movement on display

The sinker is Brooks’ best friend early in the count and when’s down in the count. He’ll use it to induce swings-and-misses against LHH in two-strike counts but it’s more of a called strike type of pitch against RHH. Hitters can sit sinker early and lefties should be wary of it late in counts; righties have another problem to worry about.


Stats for Aaron Brooks’ slider broken down by batter handedness

Brooks uses his slider against both RHH and LHH, throwing it 30% and 20% of the time respectively. In the 85–87 mph, Brooks doesn’t get a whole lot of horizontal break, but the lack of movement actually plays pretty well off of the arm-side run that his sinker and changeup get.

Locations for Aaron Brooks’ slider, broken down by RHH vs LHH

Brooks is very confident in his slider and is willing to throw it for a strike when needed, throwing it for a strike 79% of the time against righties and 78% of the time against lefties. It also does double duty against RHH, inducing a whiff rate of 27%, which is why he primarily uses it in two-strike counts, throwing it 29% of the time in 0–2 counts, 31% of the time in 1–2 counts, and 36% of the time in 2–2 counts.

Left-handed hitters don’t fare as poorly, with a whiff rate of 19% and swing at his slider the most out of any pitch he throws with a 73% swing rate. Some of that has to do with where he throws it; locating his slider in the zone is naturally going to lead to it being put in play as opposed to when he throws it inside or down. He could cut down on his slider usage to LHH, but I’d advise against it and you’ll see why when we discuss Brooks’ next pitch.

Overall, righties have to more vigilant for the slider in two-strike counts as that when Brooks uses his slider down and away for whiffs. Lefties have fared relatively well so far against his slider which he’ll usually throw when he’s ahead against lefties.


Stats for Aaron Brooks’ changeup, broken down by batter handedness

Aaron Brooks’ best pitch is his changeup against left-handed hitters. He throws it 28% of the time against lefties versus just 6% against righties, so I’ll be discussing his changeup in context against lefties. Coming in around 85 mph, just off of his slider, Brooks’ changeup has been ridiculously successful against lefties, with a strike rate of 74% and a whiff rate of 31%.

An overall whiff rate of 31% is pretty good; Patrick Corbin and Jacob deGrom had overall whiff rates of 31.8% and 31.5% last season, so having one pitch as good as those two is excellent territory. The side-to-side movement and drop off that Brooks is able to induce is remarkable and makes his changeup one of the most potent pitches I’ve seen.

Locations of Aaron Brooks’ changeups

Brooks locates his changeup down and away from lefties, maximizing the vertical break and arm-side run that he gets on the pitch. The combination of arm-side run and vertical drop that Brooks induces is absurd. At 86 mph, I don’t know how you’re supposed to hit a pitch that drops off of the end of the table like, especially breaking away from you.

Apparently, neither do KBO hitters. Brooks has thrown 53 changeups to lefties in the three games I’ve watched and has induced 10 groundouts on the pitch and 10 whiffs. That’s a ridiculous success rate and exactly what Brooks sets out to do against hitters.

Brooks doesn’t throw his changeup very much in two-strike counts, rather primarily using it in 0–1, 1–0, and 2–1 counts to set up the hitter. The best-case scenario is a weakly hit groundball or whiff, either resulting in an out unsettling the hitter. The downside of throwing a changeup in those counts is relatively minimal, resulting in a ball, but also setting up his sinker or slider if needed. Lefties need to be prepared to face Brooks’ changeup, but that doesn’t make it any easier to hit considering its similar shape to his sinker and the near-identical velocity with his slider.


Stats for Aaron Brooks’ curveball, broken down by batter handedness

Aaron Brooks rarely throws his curveball, only using it 8% of the time against RHH and 4% of the time against LHH at around 80 mph. It’s primarily a change of pace pitch for him and he gets a decent amount of strikes on it, with a strike rate of 86% against LHH. He’s thrown it 11% of the time in 1–1 counts which signals that he uses it to try and “steal” a pitch to get to a 1–2 count.

Hitters, on either side of the plate, don’t need to worry about facing his curveball. He uses it to steal the occasionally strike, but its usage is so sporadic it’s not worth trying to predict.

Recapping Brooks’ Approach

Against RHH, Brooks likes to lead with his sinker in the zone and slider down and away. His slider is his swing-and-miss pitch while his sinker is a very reliable strike whenever he wants it. Brooks’ main goal against righties is to induce soft contact on the ground and he’s excelled at that so far this season.

Lefties have to be wary of each of Brooks’ three primary pitches. His sinker is a strike pitch and he elevates it for a whiff when he needs it. His changeup is his best pitch, diving down and away to lefties and inducing a lot of groundouts and whiffs. Hitters should be trying to sit on his slider on the inner third of the plate.

Aaron Brooks always wants to induce weak contact and groundouts but is willing to go after swings-and-misses, especially against lefties.

*Stats from FanGraphs,, Baseball Savant, Sports Info Solutions, and the official KBO website*

Sophomore studying Sport Management and Economics at the University of Texas. Writing about Baseball from an analytical and scouting perspective