Justin and B.J. Upton and the Brother Effect

According to Kevin Towers, a few days ago he was prepared to move on without having traded Justin Upton, as he wasn’t finding enough value on the market. In lieu of an Upton trade, the Diamondbacks presumably would’ve made a Jason Kubel trade, presumably with the Orioles. But things changed, and they must have changed swiftly — on Thursday, the Diamondbacks officially announced an Upton trade with the Braves, as Justin will join his brother B.J. in the Atlanta outfield. Or, this, in other words.

Dave already wrote about the trade overall, from both sides. Mike Newman already took a look at the prospects involved. I, personally, got curious about the brother angle. This was something Justin was hoping for; he turned down a trade to Seattle, hoping for a trade somewhere else, somewhere more familiar, somewhere closer to home. Speculation was that he wanted Atlanta more than anything else. It’s an odd quirk that Upton will play beside his own brother. But I found myself wondering if the psychology involved has any effect on performance. In short: historically, have players gotten better when they’ve been teammates with a sibling? On one hand, it would be surprising if they did; on the other hand, it would be surprising if they didn’t. Players are always talking about the importance of comfort. What could be more comfortable than playing with family?

It’s unusual for brothers to be teammates in the major leagues, but it’s hardly unprecedented. See this information from Baseball Almanac. There have been plenty of teammate brothers, and there have been a couple teammate father and sons. Any study is still going to be based upon a limited sample, but at least there is a sample, so we might as well see what we see.

I identified brothers who became teammates after already having gained major-league experience. In this way, I could track their performances in the year before they became teammates, and in the year after they became teammates. It stands to reason this is where we could see an effect. For hitters, I looked at wRC+, and for pitchers, I looked at ERA-. I considered post-war major-league baseball, because I’m not real interested in what happened before then, and I set arbitrary minimums of 100 plate appearances for hitters and 40 innings for pitchers. In the event that brothers became teammates, split, and then later became teammates again, I counted them multiple times.

Understand that we’re working with a very limited sample. Understand that this isn’t fantastic science, and understand that there are multiple potential sources of error. But what you want are results, so here are some results:


Year before teammates: 110 average wRC+
Year after teammates: 114 average wRC+


Year before teammates: 93 average ERA-
Year after teammates: 102 average ERA-

There’s nothing real eye-opening. The pitchers have actually gotten worse, but our sample is 17 individual player seasons, our difference is nine points, and our statistic is based around ERA, which as you know includes a lot of noise. With the hitters, there’s a four-point improvement, but given all the noise we can’t reach conclusions from that. We don’t have evidence that players hit a lot better, nor do we have evidence of the opposite. What our evidence suggests is that players remain more or less the same, which would be fairly intuitive.

Jason Giambi took a big step forward when he was joined by brother Jeremy in Oakland in 2000. Roberto Alomar and Sandy Alomar improved between 1998 and 1999. But then, Scott Hairston struggled alongside Jerry in 2010. Adam LaRoche didn’t do much for Andy LaRoche. The results are mixed, just as you’d think they would be.

I’m sure it’s a neat experience to play on the same major-league team as a sibling. Even if you aren’t particularly fond of that sibling. That doesn’t mean a player’s likely to improve, though, at least not because of the teammate reason. It turns out baseball is a complicated game the outcomes of which can’t be determined by one’s emotional state. Play with a brother in April and, chances are, come July or August, it just feels like regular baseball. Chances are even in April it just feels like regular baseball, with maybe a good friend in the clubhouse.

Of course, what applies generally doesn’t have to apply specifically, and the Upton brothers are unique, like all sets of brothers. Both are known for their incredible raw skillsets, and both are known for not consistently reaching their ceilings. Maybe each will be motivated in Atlanta by the presence of the other. Or maybe B.J. will just be happy to be away from Tampa, and Justin will just be happy to be away from Arizona. Maybe they don’t improve. Maybe they stay the same, or even get worse. At the end of the day, they’re just two teammates in major-league baseball who know each other pretty well.

It’s going to be weird for Jason Heyward, though. No one likes feeling excluded.

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Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

31 Responses to “Justin and B.J. Upton and the Brother Effect”

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  1. TheHoustonian says:

    Does this adjust for Marcus Giles being an atrocious hitter for the Padres?

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  2. rusty says:

    Is the 110 wRC+ in the “before” year interesting enough to merit any further investigation? Like something about growing up in a “baseball family” or whatever? Something like Cheryl and Reggie Miller, maybe.

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    • Anon21 says:

      I mean, what are the odds that in picking any couple dozen individual player seasons, minimum 100 PA, that you’ll come up with a wRC+ of 110? Decent, it seems to me.

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      • Jeff says:

        Considering that the chances of playing seasons both with and without a sibling go up as the number of seasons a player plays increase, it’s not surprising that it’s an above average wRC+. Players at or above league average play more seasons than those who aren’t.

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  3. Hurtlockertwo says:

    Interesting list, I feel bad for the brothers of the HOF players.

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  4. Baroque says:

    If Cal Ripken made Billy Ripken better, it’s funny to think how bad Billy would have been without him.

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  5. Redscot says:

    Just want to take this moment to give a shout out to the Alou brothers (Felipe, Jesus, Matty) who shared (not started) in the same outfield for the Giants in 1963. There were many challenges culturally and other, and the predominance of Dominican players was years away. Can’t think of a prouder pop in that moment!

    To the matter at hand, have B.J. and J in one of my ottoneu teams, so here’s hoping for the best!

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  6. AC of DC says:

    From the headline, I thought this was going to be about Integration.

    (No I did not.)

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  7. Voice of Reason says:

    In a sample size of one, Jason Giambi could apparently not induce his brother to slide.

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  8. Bip says:

    I once heard that while Ramon Martinez was at his peak for the Dodgers he told the management that his younger brother, Pedro, was even better than he was. They should have listened.

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  9. Ozzie Guillen says:

    What do you mean Jason Heywards not their brother?

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  10. In August both Upton brothers hit their 100th career home run on the same night, which prompted me to look at brothers throughout baseball history. There have been almost 400 sets, and I listed my top twenty:


    I’m envious of Braves fans getting to watch both of them AND Jason Heyward for the next 3+ seasons.

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  11. jimbo says:

    if you filter the list of siblings down to only those with at least one all-star appearance, does it change the totals?

    i’m just wondering how many lower-end talents weren’t going to improve no matter if gramma was in the dugout. the upton boys certainly have more ability than some family names mentioned in the article.

    great angle though, and quick too!

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  12. shthar says:

    No we need a father/son effect article.

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  13. The Rajah says:

    Maybe the Braves will invite Eric Carmen to sing the national anthem on opening day in honor of Jason Heyward.

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  14. Keith says:

    Excellent question/story angle, well answered. Is there any trade/other typed of transaction that does have a marked effect on performance? Getting traded to one’s hometown, for instance?

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  15. jdm says:

    Did you account for park changes? If a player changes from Petco to Arlington that will have an effect on their performance changes

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  16. Hurtlockertwo says:

    makes you wonder if some of these brothers would have even made it to the majors if not for their brother’s accomplishments?? Tommie Aaron? Ozzie Canseco?

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  17. JeffS says:

    I disagree with the Jason Heyward being excluded…he will turn into the leader and captain of this team. Braves will go where Jason goes this year

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  18. Mario Mendoza says:

    But…. NARRATIVE!!!!!

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  19. JKB says:

    You show that the average of the two brothers does not change much YOY. However, there is usually one brother that is better than the other.

    If you created an “superiority flag” indicating the “better” vs. “worse” brother, it would be interesting to see a YOY comparison like you did above, but for the “better” brothers separate from the “worse” brothers. Maybe one would go up while the other goes down?

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  20. Oh, Beepy says:

    While interesting, a quick glance over that list reveals to me that the Uptons may be a unique case in regards to the parity of their skill levels. I don’t think two brothers with the talent level of BJ&J, both in their respective primes and as yet having not realized their obvious potential, necessarily has any precdent to speak of. The case can be made in a lot of those cases that the inferior brother was brought in as more of a publicity stunt whereas the Braves legitimately got two of the best available outfielders who happened to be brothers.

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    • Brad says:

      I agree. I’d like to see some of the lesser brother pairs excluded (Jose and Ozzie, Cal and Billy, etc.) to see if that changes the impact. Moreover, while I have no idea how to measure it, I would think the impact of a brother would also be based on the relative “closeness” of the brothers (e.g. multiple Alou brothers may not be as close as the Uptons). With that being said, I agree with the article’s conclusion that the effect of brothers will probably disappear quickly…maybe the only lingering impact of brothers would maybe be slightly shorter slumps (because the other brother may be able to quickly advise on mechanics) and more coach/manager firings (because of the increased influence on clubhouse morale and opinion).

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  21. Antonio bananas says:

    Did you neutralize for age? If Justin has a significan increase in production and bj stays relatively the same, that’s likely the normal course. With the Giles brothers, Marcus I believe was older and declining.

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