Tight ends vs. running backs: turn angle concentration

Determine whether tight ends exhibit more concentrated directional movement than running backs in NFL ball-carrier sequences, as measured by the turn angle concentration parameter (kappa) of a von Mises Bayesian circular mixed-effects model that includes fixed effects for speed, acceleration, cumulative distance covered, play type, and a position indicator, along with player-level random intercepts grouped by position.

Background

The paper models frame-level turn angles for NFL ball carriers using a Bayesian circular mixed-effects framework with a von Mises distribution. The concentration parameter (kappa) quantifies consistency in directional movement, with higher values indicating more concentrated (less variable) turning behavior.

In the fixed-effects analysis of the concentration model, the coefficient for tight ends is positive, suggesting potentially more concentrated turning relative to running backs. However, the 95% credible interval includes zero, leaving the comparative relationship unresolved. This motivates a concrete question about whether tight ends indeed display greater turn angle concentration than running backs when accounting for specified covariates and random effects.