Overlay Comparison

Stack multiple pitches to compare trajectories

Overview

Overlay mode lets you simulate multiple pitches and display their trajectories simultaneously. This is the core feature for pitch comparison — tunneling analysis, pitch design evaluation, and consistency checks.

Turning On Overlay

Check the Overlay checkbox next to the Simulate button. Once enabled:

  • The first pitch clears the view and draws normally
  • Each subsequent pitch adds its trajectory on top, in a different color

Overlay comparison showing two pitch trajectories

Two pitches overlaid — FF (orange) and ST (green) with different trajectories

Selecting Multiple Pitches at Once

When viewing a game’s pitch list, you can select multiple pitches:

Action Effect
Cmd/Ctrl + Click Toggle individual pitches on/off
Shift + Click Select a range
“All FF (12)” button Select all pitches of a type
“Clear All” button Deselect everything

When multiple pitches are selected, the Simulate button changes to “Simulate N Pitches (Overlay)”. Click it, and all selected pitches are simulated sequentially with automatic overlay.

Warning

Selecting more than 30 pitches triggers a confirmation dialog. Each pitch requires an API call, so large batches take time.

Animated Playback

When overlaying multiple pitches:

  • Up to 3 balls animate simultaneously during playback
  • Each ball is a textured baseball rotating at its real angular velocity
  • Balls are time-synchronized — a 155 km/h fastball arrives at home plate before a 130 km/h curveball
  • After the fastest ball arrives, playback continues until the slowest ball reaches home plate
  • Frame stepping (← → keys) covers the full time range including slower overlay balls

Overlay Statistics

After overlaying 2 or more pitches, the Overlay Statistics panel appears in the left panel (scroll down). It shows:

Input Parameters

  • Speed, release position, angles, BSG spin components, angular velocity (ωx, ωy, ωz), |ω|, component ratios

Simulation Output

  • Home plate crossing, spin movement, Statcast comparison, tunnel point

Statcast Measured

  • SC Move Horiz/Vert (cm) — the actual Statcast-measured spin movement (pfx)

All values show Mean ± σ, Min, Max. The section is collapsible.

CSV Export with Statistics

When you click CSV Export with overlay data:

  • The summary CSV includes one column per pitch, plus Statistics rows (mean, std, min, max) at the bottom
  • The trajectory CSV includes all pitches side by side

Tips

  • Overlay FF + ST to evaluate fastball-sweeper tunneling
  • Overlay all FF in a game to check fastball consistency (look at standard deviation)
  • Use Batter’s Eye view with overlay to see the pitches from the hitter’s perspective
  • The Tunnel button shows the 23.8-ft tunnel cylinder for each pitch