How important are hot streaks for hitters?

During my appearance on TribLIVE Radio’s fantasy show last week (you can hear the audio recording of it here), the topic of hot and cold players came up a few times. My general response was that I don’t put a whole lot of credence into hot and cold streaks because I don’t believe that a handful of plate appearances – even if they’re the most recent handful of plate appearances a hitter has – can be more predictive than what several year’s worth of plate appearances can tell us about the hitter.

While there have been some studies conducted on this topic in the past, I thought I’d conduct my own today, putting a FanDuel spin on it, to see if my theory holds any water.

The Study

To study this, I decided to look at 7-day “hot” streaks, comparing the stats from the hitter’s 7-day streak to the following day’s stats (day eight). I’d then compare the hitter’s preseason Marcels projection to the hitter’s day eight stats. This will tell us which is more predictive – a full projection for a player or the streak. When comparing these sets of numbers, I’ll be using average error to study the differences.

I looked at all possible 7-day streaks for all hitters back to 1993 that occurred in either March, April or May (I did this so that the preseason projections would be as accurate as possible – if we’re looking at streaks in August, it’s likely the player’s projection would have changed considerably by that point in the season). From there, I included all hitters who had played in at least five of the past seven days and who had at least three plate appearances on day eight. No context adjustments were made to the data.

“Hot” Hitters – 7 days

While I’ll be looking at a number of different stats, I decided to define a “hot” streak based upon FanDuel points accumulated (based on FanDuel’s MLB 35k format). The average hitter accumulates roughly three points per game, so to be included among the “hot streak” population, a hitter must have averaged at least six FanDuel points over a seven-day period. Here are the average errors for a number of different stats (keep in mind that the lower the number, the better). (All stats were scaled to league average before comparison except FanDuel points for clarity’s sake)

Here, we see that in all of the categories we look at, the preseason projection proves to be far more reliable in predicting future performance than the hot streak does.

If we chose to use a hitter’s 7-day hot streak to predict his next day performance, we would misestimate him that day by nearly five points, while using his preseason projection would have caused us to be wrong by just two points.

Perhaps seven days isn’t long enough, though. After all, it’s merely a week, a most players only play five games per week.

“Hot” Hitters – 14 days

So let’s repeat our study using 14 day hot streaks. The only thing that changes is that we require the player to have played on 10 of those 14 days.

Nope. Again, we find that the preseason projection is better suited to projecting future performance than the hot streak is. The 14-day streak is better than the 7-day streak, however. Marcels was better than the 7-day by 2.43 FanDuel points but was better than the 14-day by just 1.76 FanDuel points. Let’s try once more…

“Hot” Hitters – 30 days

What happens if a hitter manages to keep up a hot streak for a month (playing at least 21 of the 30 days)?

Again, the streak becomes more predictive (now it’s just 1.33 FanDuel Points worse than Marcel), but we’re still better off with the preseason projection.

Final results

No matter how long a hot streak lasts, it appears that using a projection (even a preseason projection as simple as Marcel) is far superior than trusting that the streak will continue.

Concluding thoughts

Before I wrap up for the week, I have a couple of quick announcements that I hope you’ll stick around for.

First, as you probably know, I’ve been the Fantasy Manager of The Hardball Times for the past four years. I’ll soon be leaving THT and joining Baseball Prospectus, so be on the lookout for my first article over there on Monday.

Additionally, I also post to the website of the CardRunners Experts League. This week, I began a series looking at the value and reliability of closers. The first article in the series looks at how likely a closer is to keep his job the entire season.

Finally, I’ll be a guest on TribLIVE radio’s fantasy program again today at 4:30 PM EST. You can listen in live here.

If anyone has any questions, as always, feel free to comment or e-mail me. Also, be sure to add me as a friend on Facebook and follow me on Twitter.

Derek Carty’s work can also be found at Baseball Prospectus, CardRunners Fantasy Baseball, and DerekCarty.com. He has previously had his work published by The Hardball Times, NBC’s Rotoworld, Sports Illustrated, FOX Sports, and USA Today. He is the youngest champion in the history of LABR, the longest-running experts league in existence, and is a graduate of the MLB Scouting Bureau’s Scout Development Program (aka Scout School). He welcomes questions via e-mail, Facebook, or Twitter.

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