Intermediate

平飞球率

Also known as: LD%, 平飞球比例

Definition

平飞球率（LD%）是指被归类为平飞球（通常发射角0-25°且击球力量强劲）的击球所占的百分比——是所有击球类型中预期打击率最高的一类。

平飞球在所有击球类型中拥有最高的预期打击率，因为它们击球力量强劲、在空中停留时间足以安全落地，同时又难以被防守方处理。一般认为25%以上的LD%属于顶尖水平。打者可以通过优化棒头路径、让其更长时间保持在投球平面上，减少翻腕，以及改善攻角以匹配来球的下行轨迹，来提高自己的LD%。相比小样本下的打击率，LD%是衡量真实接触质量更稳定的指标。

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

她28%的平飞球率是其接触质量最清晰的证明——她持续稳定地匹配投球平面，扎实地打中球心。

Why it matters

SwingVantage对棒头路径、攻角和接触一致性的分析，直接映射到平飞球率背后的机械驱动因素——分析中的改进会转化为击球质量的真实提升。

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.