Hot Streaks and "Luck" in Baseball

[Stoneyen]

This is something I've been trying to wrap my head around for a little while now. We've all seen the dramatic effects of small sample sizes on players' performance that produce "hot streaks" or "slumps" or lead analysts to say the player is dialed in. What I've been thinking about is whether this is simply random variance or "luck" (with the player always performing at the same level) or is it an actual physical or mental change in the player's approach that goes through normal fluctuations.

 

Ex: If a batter goes 18-33 with 8 XBH and 4HR, is that just a string of BABIP luck and HR/FB luck? Or is it a stretch where the player was seeing the ball exceptionally well and physically "dialed in" and making better contact because of an optimal approach/performance. In the first scenario this sting of positive random variance would be balanced by equal streaks of negative random variance so that over the long haul the batter regresses. Where as in the second scenario the stretch of optimal performance would be balanced by a stretch where the batter wasn't having the same mental and physical approach/performance.

[Abomination]

This is something I've been trying to wrap my head around for a little while now. We've all seen the dramatic effects of small sample sizes on players' performance that produce "hot streaks" or "slumps" or lead analysts to say the player is dialed in. What I've been thinking about is whether this is simply random variance or "luck" (with the player always performing at the same level) or is it an actual physical or mental change in the player's approach that goes through normal fluctuations.

 

Ex: If a batter goes 18-33 with 8 XBH and 4HR, is that just a string of BABIP luck and HR/FB luck? Or is it a stretch where the player was seeing the ball exceptionally well and physically "dialed in" and making better contact because of an optimal approach/performance. In the first scenario this sting of positive random variance would be balanced by equal streaks of negative random variance so that over the long haul the batter regresses. Where as in the second scenario the stretch of optimal performance would be balanced by a stretch where the batter wasn't having the same mental and physical approach/performance.

 

It's almost certainly a combination of random variance, mental variance, and other factors. Negative stretches could be affected by things like minor injury, fatigue, or soreness. The eye level of the batter combined with arm height and angle of the pitcher could place the ball coming out of a different location of the batting eye. Some batters react to weather differently (I assume), etc. It's very difficult to determine what is random variance, and what is caused by variables you haven't considered in your model (or perhaps variables you simply don't have access to).

[Stoneyen]

It's almost certainly a combination of random variance, mental variance, and other factors. Negative stretches could be affected by things like minor injury, fatigue, or soreness. The eye level of the batter combined with arm height and angle of the pitcher could place the ball coming out of a different location of the batting eye. Some batters react to weather differently (I assume), etc. It's very difficult to determine what is random variance, and what is caused by variables you haven't considered in your model (or perhaps variables you simply don't have access to).

 

 

I agree that it's a combination of both. I really like that idea that part of what we see as random variance is variables we aren't aware of yet or maybe can't fully quantify (yet). Kind of how statcast is opening the window into more batted ball stats and spin rates.

[RealAccountant]

I've always wondered if all hitting in RISP is luck, or are there hitters genuinely worse or better with RISP.