Intermediate

ライナー率

Also known as: LD%, ライナー率

Definition

ライナー率(LD%)は、打球のうちライナー(一般的に打球角度0〜25度、かつ強い打球)に分類される割合のことで、打球タイプの中で期待打率が最も高い。

ライナーはどの打球タイプよりも高い期待打率を持つ。強く打たれ、安全に落ちるだけの滞空時間があり、守備が難しいためだ。一流のLD%は一般的に25%以上とされる。打者は、投球の軌道面により長くバレルを保つようバレルパスを最適化し、ロールオーバーを減らし、投球の下向きの軌道に合わせてアタックアングルを改善することでLD%を高められる。LD%は、少ないサンプルにおいては打率よりも安定した真のコンタクトの質の指標だ。

Beginner tip

During tee work, focus on hitting the back half of the ball. This means the part furthest from the pitcher. This means and drive it straight back through the imaginary pitcher's mound. This produces the contact geometry that generates the highest line drive rate.

Advanced note

Compare your LD% data across pitch velocity bands in your SwingVantage session reports. This means a significant LD% drop on high-velocity pitches confirms a timing cause. A consistent LD% decline across all pitch speeds confirms a barrel-path or contact-point cause that does not depend on timing.

Example

彼女のライナー率28%は、コンタクトの質を最も明確に示す指標だった。彼女は一貫して投球の軌道面に合わせ、芯で捉え続けていた。

Why it matters

SwingVantageによるバレルパス・アタックアングル・コンタクトの一貫性の分析は、ライナー率を左右するメカニクス上の要因に直接結びついている。この分析で得られる改善は、実際の打球品質の向上へとつながる。

How it shows up on video

On video, line drive production is associated with a barrel that arrives at the contact point on a matching plane to the pitch trajectory. This makes contact at or slightly above the ball's equator. Common errors that suppress line drive rate include a barrel arriving below the pitch plane (undercutting. This produces pop-ups), a barrel arriving from above the pitch plane (chopping. This produces grounders). A barrel arriving after the optimal contact zone with the arms still bent (producing weak, pull-side flares rather than hard-hit drives).

Common mistakes

Confusing line drives with "contact hitting" and reducing swing aggressiveness in an attempt to make more contact. This means line drives require hard barrel contact, and pulling back swing intensity produces soft grounders and flares rather than true line drives
Using a barrel path that is too flat or downward across all pitch heights rather than adjusting attack angle to match specific pitch locations. This means middle-height pitches need a flatter approach than low-in-the-zone pitches
Treating LD% as a random outcome rather than a mechanical metric. This means over a sufficient sample, LD% is one of the most mechanically stable statistics available and should be used as a training target
Neglecting the attack angle dimension of line drive production and working only on barrel path without also verifying that the approach angle at contact is in the 10–25 degree window that produces true line drives rather than flat grounders

In SwingVantage Motion Lab

SwingVantage correlates barrel path angle and contact location on the ball's surface with batted-ball outcome categories. This builds a session-level line drive rate estimate from mechanical data alone. Pitchers see a suppressed LD% metric that quantifies how effectively their pitch movement and location is preventing clean barrel contact across rep sequences.