内野の深さ
Also known as: 内野の位置取り, 前進守備, 定位置守備
内野の深さとは、内野手がホームベースからどれだけ離れてプレーするかということです。「前進」(得点を防ぐために前に詰める)か「定位置」(ゴロやライナーへの守備範囲を最大化する標準的な深さ)かのいずれかです。
三塁に走者がいて1死のスローピッチの場面では、内野はコーナーで「前進」し、走者が得点する前にゴロを刺そうとすることがあります。これは強い当たりへの守備範囲が狭まるというトレードオフを受け入れることになります。標準的な深さ(定位置)は、どんな打球に対してもアウトを記録できる確率を最大化します。深く守りすぎると、遅いゴロで走者に得点を許してしまいます。浅すぎると、打者に外野へのより大きな隙間を与えてしまいます。深さの判断は、スコア、イニング、アウトカウントに基づいて投球前に行われます。
As a new infielder, play at standard depth until you understand your reaction time and throwing arm. This means then start adjusting based on the batter's known tendencies.
Use spray charts from prior at-bats to set exact infield depth for each batter. This means the right positioning before the pitch eliminates the need for difficult reactions after contact.
Example
三塁に走者、1死の場面で、三塁手と一塁手は前進し、同点となりうる走者をプレートで刺そうとする。
How it shows up on video
Infield depth is a pre-pitch positioning adjustment visible before each at-bat. Playing in (shallow) means infielders are near the basepath, positioning for a home-plate throw or preventing a slow roller from becoming a hit. Playing back means standard depth near the base. Camera angles from center field best reveal these adjustments.
Common mistakes
- Playing the same depth for every batter regardless of their speed, power, or tendency to pull the ball
- Forgetting to communicate depth adjustments to all infielders, creating uneven positioning across the infield
- Playing too shallow with less than two outs and the bases loaded, giving up extra-base hits for a home-plate play that may not happen
- Not adjusting depth based on game situation — a one-run lead late in the game calls for different positioning than a blowout
In SwingVantage Motion Lab
SwingVantage can map batted-ball spray charts from uploaded video, helping teams identify where to position infielders based on individual batter tendencies.
Related terms
Related guides & benchmarks
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