What did the Royals miss with Brent Rooker?
The former Royals outfielder has become one of the league’s top sluggers.
At the 2022 trade deadline, the Royals were far out of contention. It was another rebuilding season as the team tried to build up a farm system decimated after their championship runs. The team would go on to 97 losses, so there was no point to keep veterans like Whit Merrifield or Andrew Benintendi, both of whom were traded to contenders. The Royals also traded catcher Cam Gallagher to the San Diego Padres, in return for a 27-year-old former-first round pick in the outfield, Brent Rooker.
Rooker would play all of 14 games with the Royals before they lost him in an offseason roster shuffle to the A’s. He would hit 69 home runs over the next two years, hitting .272./.348/.528. He would be named an All-Star in 2023, and won a Silver Slugger Award in 2024, earning him a five-year, $60 million contract extension this week.
What did the Royals miss here?
Brent Rooker was a first-round pick by the Twins out of Mississippi State in 2017 a few picks ahead of future Royals like Drew Waters and MJ Melendez. He immediately mashed and made Baseball America’s top 100 prospect list, but he had a lackluster second pro season in Double-A and lost the entire 2020 season due to the pandemic.
So by 2021 he was a 26-year-old in Triple-A, but he was absolutely mashing with 20 home runs in 62 games. The Twins brought him up for 58 games and he struggled, hitting 201/.291/.397 with nine home runs. He struck out 32 percent of the time and whiffed on 37 percent of all breaking balls he saw. The Twins were pretty loaded with young outfielders they wanted to look at - Byron Buxton, Max Kepler, Trevor Larnach, Alex Kirilloff, Nick Gordon, Jake Cave, Rob Refsnyder, and Kyle Garlick were all in the organization at the time. So at the beginning of the 2022 season, they packaged him with Taylor Rogers in a trade with the Padres for Chris Paddack and Emilio Pagán.
Rooker again mashed in Triple-A with 19 home runs in 61 games in the thin air of El Paso, Texas. The Padres never called him up, instead sending him to the last-place Royals in August. After two weeks in Omaha, the Royals called him up and he went 2-for-3 with a double in his debut.
But playing time was sparse. Rooker was on the roster from August 10 to September 9 and appeared in just 14 games with 29 plate appearances. In that time they gave more plate appearances to MJ Melendez (110), Michael A. Taylor (94), Hunter Dozier (73), Kyle Isbel (56), Drew Waters (55), and Nate Eaton (35). Rooker didn’t set the world on fire in his 29 trips to the plate in a Royals uniform. He went 4-for-25 with the double in his debut as his only extra base hit. He walked three times and struck out seven times. He was sent down in September so Vinnie Pasquantino could be activated from the Injured List and did not return the rest of the season.
On November 15, the Royals designated Rooker for assignment to make room to add Alec Marsh, Freddy Fermin, and Diego Hernandez and to re-sign Ryan O’Hearn. Two days later, the A’s - who were #2 in waiver priority - claimed Rooker off waivers and the rest is history. He made the team in 2023, smashed nine home runs, and hit .353 in April en route to an All-Star season.
There are a lot of sluggers like Rooker in Triple-A, and like him they pound mistake fastballs by sloppy pitchers. They’re also pretty one-dimensional, so they need to hit to have any value. But when many of them get called up, they have trouble with big league breaking balls, like the fictional slugger Pedro Cerrano from the film Major League. This was true for Rooker too. He hit .307 and slugged .613 against fastballs in 2023, but just .141 with a 53 percent whiff rate on breaking balls.
But unlike many of those Triple-A sluggers, Rooker adjusted. This year he hit breaking balls, batting .259 with 13 of his home runs coming off them. Overall he cut down on his strikeout rate, improved his walk rate, and increased both his hard-hit rate and average exit velocity. As Esteban Rivera at Fangraphs writes, he did this by flattening his swing.
On average, Rooker’s swings were flatter at contact, giving him a better chance to be effective at the top of the zone where pitchers were likely to target him this season. He took the biggest hole in his game and made it a smaller one; as a result, his strengths played up more....
Typically, batters raise their hands to make it easier to maintain a flatter barrel, make contact deeper in the zone, and shorten their swing length. That all sounds wonderful, but some sluggers refrain from this adjustment because it becomes more difficult for them to create launch. Turns out, that wasn’t the case for Rooker; his flatter swing was still steep enough to crush balls in the air.
Whether he would have made that adjustment in Kansas City or not is something we’ll never know. We do know that the Royals could use a bat like him now. His .365 on-base percentage last year was better than anyone on the Royals other than Bobby Witt Jr. and 36 of his 39 home runs were deep enough to be gone at Kauffman Stadium. I don’t blame the Royals for letting him go - no one really knew he would develop like this.
If there is a lesson to be learned, it might be to give players in the minors with an exceptional skill set a chance to adjust at the big league level. Everyone knew Rooker had superior power, but they questioned whether he could make enough contact for it to count. But all he needed was an adjustment to improve his contact rates, and voila, you have an All-Star slugger.
There are a lot of guys like this in Triple-A - the Royals have one in Nelson Velázquez. In fairness to the team, they have given him a good opportunity and aside from a hot month in 2023, he hasn’t really produced. And now they’re in contention mode where they can’t really afford to give a 27-year-old Triple-A guy 200-300 plate appearances to figure things out.
But if this team ever rebuilds again, it might be worth remembering guys like Brent Rooker.