I wanted to take a break from my Effective Velocity research, and so, in honor of Anthony Rendon, I decided to take a look at streaky hitters. Before this season, I did not have a perception of Rendon as streaky. But so far this season, he has produced 5 of his 7 total home runs, 7 of his 21 total runs, and 15 of his 28 total RBI in just two games. That’s insane. It may not mean anything in this case; however, it makes intuitive sense that some hitters would be more consistent than others. And beyond even the desire to roster consistent hitters over streaky hitters in weekly formats, I think it is at least worth exploring whether it is possible to identify hot and cold streaks as they are happening and make start-and-sit decisions with them in mind.
The first step toward that goal is defining what hot and cold streaks are. Rendon probably isn’t the best example of that. In general, I think of a hot hitter as one who produces well above his typical level of production for an extended period. As a starting point, I decided to look at players who produced a wOBA over seven consecutive games or more that was either 110 points above their seasonal line (hot) or 110 points below their seasonal line (cold). That 110-point threshold is fairly random, but it is based on the difference in the glossary markers for an excellent and awful player over a full season.
The tricky part is in handling overlapping streaks. When someone has a game like Rendon did on Tuesday, you can create a seven-day hot streak that includes it, an eight-day hot streak that includes it, and so on. My preference is to consider only the longest such streak as a hot streak and throw away all of the other streaks that are contained within or overlap with that streak. That said, I opted to allow hot streaks and cold streaks to overlap with each other. For example, in 2017, Rendon has two streaks based on my specifications. His first is a cold streak that lasted from April 2 through April 29, and his second is a hot streak that lasted (so far) from April 27 through yesterday—not surprisingly, that hot streak is more-or-less bookended by those two monster games. It’s not perfect, but I think it produces a fairly accurate count of streaks for hitters.
So far in 2017, there are 11 players with at least 4 total streaks: Ender Inciarte, Yangervis Solarte, Carlos Gonzalez, Trevor Plouffe, Ezequiel Carrera, Lorenzo Cain, Andrelton Simmons, Adam Duvall, Kole Calhoun, Delino DeShields, and Max Kepler. But I don’t expect there to be a clear takeaway from those results because hitters have had less than two months to establish their seasonal baselines. Instead, I think it’s more instructive to look at full seasons, and I’ll be using a 300-plate-appearance minimum to further stabilize player seasonal expectations.
In 2016, Gregory Polanco had the most streaks in baseball with 8. Kris Bryant had the second most with 7. It makes sense that players with excellent power like Bryant would be more prone to hot and cold streaks because home runs produce the biggest change in wOBA of any possible event. After those top two streaky hitters, there were 23 hitters with 6 streaks, including notable fantasy players like Carlos Correa, Chris Davis, Nelson Cruz, Mark Trumbo, Daniel Murphy, and Jason Heyward. Most of the players with fewer streaks were consistently bad, but Joey Votto, Ryan Braun, Yoenis Cespedes, and Dexter Fowler were some notable productive players with only 2 streaks.
For research purposes, more interesting than the players themselves is the typical length of these streaks.
In general, there is a consistent downward trend, which matches up with the expectations I had. However, it looks like it is pretty common for streaks that last at least 7 days to continue to last up to about 21 days, at which point the frequency really drops off of a cliff. That trend bodes well for the idea of identifying a streak while it is happening, which is something I’ll dig into more in future weeks.
Scott Spratt is a fantasy sports writer for FanGraphs and Pro Football Focus. He is a Sloan Sports Conference Research Paper Competition and FSWA award winner. Feel free to ask him questions on Twitter – @Scott_Spratt