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For about a month, Miami Marlins outfielder Justin Ruggiano could not buy a base hit. He was 0-for-42 at-bats with eight walks in 51 plate appearances. There seemed to be no end in sight, as he was just five hitless at-bats from setting a Major League record of great disappointment. It would have been another failure in a series of difficulties with the Malrins' offense.
Then, all of a sudden, Ruggiano broke out. On August 14, he got three singles in four plate appearances. On August 16, in an offensive shootout in which he was not expected to play, he came in, had four plate appearances, and hit two home runs and a double. All of a sudden, it looked as though he snapped out of one of the ugliest slumps in Marlins history.
But how can that be? How can Ruggiano just suddenly come out of such a horrific slide out of nowhere, with no rumor or information of changes in his approach? It sounds as though manager Mike Redmond was simply waiting out the slump with patience more than any instruction.
"The patience [Redmond] had with me when I was going through a rut, I have so much respect for what he did when I was doing nothing," Ruggiano said. "The decisions he makes the rest of this year, I'm always going to have his back. I'm here to do whatever job he wants me to do."
There is no reason to believe that Ruggiano simply "figured it out" all of a sudden or found some mechanical tweak that gave him back his hitting. The more plausible explanation is that he simply recovered at random, with regression to the mean bringing him back up to snuff. Indeed, making decisions based on these slumps is a losing proposition when compared to simply adjusting for and expecting regression. Redmond himself hinted at that.
"It's funny," Redmond said. "When [Ruggiano] was 0-for-38, you guys thought I was crazy playing him over Stanton. Now that he is 6-for-8, you are wondering why I'm not playing him? It's funny."
What is the lesson that we can learn from here? Unless there is something physically obvious, with either mechanical or injury problems, streaks are not predictive of future performance.
The Streakiness of Streaks
In chapter two of The Book: Playing the Percentages of Baseball, Tom Tango, MGL, and Andy Dolphin went into detail about the prediction capabilities of "hot" or "cold" streaks and found that they generally do not tell us anything more than a player's career statistics. They studied the effects as follows:
This chapter looks at what happens exactly one game immediately following a five-game hot or cold streak, as well as what happens over a five-game period immediately following that same hot or cold streak. If the fans, commentators, and pundits are right, players. as a group, will hit significantly better than their own normal level of performance for some period of time following a hot streak, and significantly worse following a cold streak.
Keep in mind that the five-game streaks had to include at least 25 plate appearances.
The results of The Book's study were fascinating and unsurprising. When looking at players with a wOBA (Weighted On-Base Average, a total offense statistic encompassing all hits, walks, and outs a player makes into a number scaled to OBP) of .587 (!) during these five-game hot streaks, their expected wOBA based on their three-year history was at .365. Their actual wOBA in the subsequent game was .369. Their expected five-game post-streak wOBA was .365, and their actual value was .369.
The cold streaks acted similarly. The average wOBA of these five-game cold streaks was at .151, the equivalent of the league-average pitcher this season. The expected wOBA in the following game was .336, while the actual value was .330. In the subsequent five games, the expected wOBA was .337, while their actual value was .332.
In other words, while these hot and cold streaks did indeed drop the average expectation, that drop was ever-so slight and did not represent a significant change in talent of these players. For five games after a nasty cold streak, you would not expect the average player to show significant signs of struggling compared to their expected norms.
The Meaning of Streaking
What does this mean for analyzing streaks? Quite simply, it means that you should not analyze them. It means that looking into why a player is 0-for-20 in his last few games means nothing in the long run. It does not mean that tomorrow, the player will continue this skid or get a single or hit two home runs. Going 0-for-20 is, like most other statistical anomalies in baseball, a random happenstance. For the majority of players, it means nothing and should be treated as such.
The same goes for the positive streaks. We revere the concept of a hitting streak, but aside from the statistical oddity of it all, hitting streaks are not significantly capable of guessing the future of the player. Emilio Bonifacio had a nice long 28-game hitting streak in 2011, during which he hit .390/.479/.430 in 119 plate appearances. How did he hit for the rest of the year? He hit .298/.333/.407 in the remaining 267 plate appearances and hit .238/.295/.322 for the next two years. Ed Lucas started the year hitting .299/.371/.356 in 100 plate appearances. SInce then, Lucas has had 152 plate appearances and hit .201/.258/.266.
Clearly, Bonifacio and Lucas, like most players, "cool down" in the sense that they generally return to their baseline production.
That does not mean that streaks don't exist, or that hitters are not playing better during streaks. The numbers do not lie about how much better those players are playing. There are factors beyond mechanical concerns or physical limitations that could contribute to playing better or worse. Streaks exist, and they are real. The problem is that we do not know when those streaks will end, and the streak itself cannot tell you that.
Managers like Mike Redmond should not simply trust a small sample of 50 plate appearances to tell them that a player is "cold" and needs more time on the bench. Likewise, they should not promote a hot hitter just because he has 12 hits in 20 plate appearances. What you should trust is the player's entire history, not just what has happened most recently. Yes, what has happened recently should be given the most weight, but 20 more heavily-weighted chances should not overwhelm 1000 plate appearances of history. Without a physical change, guys do not simply become stars or scrubs overnight, nor do they turn back into those players all of a sudden. Even if they did, there is no way to make that prediction based off of a few recent chances.
When in doubt, turn to history. Justin Ruggiano and Mike Redmond were patient, and history finally rewarded them a little. Hopefully that continues to happen.