| Summary: | 碩士 === 國立臺灣體育學院 === 運動管理學系碩士班 === 96 === The analysis of baseball statistics can provide objective evaluation of performance and help to estimate fatigue and recovery levels. Many pitchers often suffer from injuries during seasons, get injured after an overused season, or perform poorly after several heavy-workloaded seasons. The injuries and performance declines may be related to overuse. The objective of this study is to investigate the appropriate way of using relief pitchers so that they could be protected from possible injury and performance decline in Major League Baseball (MLB) and Chinese Professional Baseball League (CPBL). The study compared the performance of relief pitchers with different innings pitched with their performance in the following 2 seasons. Relief pitchers in MLB with 50, 60, 70, 80, 90, or 100 innings pitched during 1982 and 2007 were analyzed. Relief pitchers in CPBL with 50, 60, 70, 80, 90, or 100 innings pitched during 1990 and 2007 were also analyzed. In addition, the performance of Major League Baseball relief pitchers with 25, 30, 35, 40, 45 or 50 innings pitched before All-Star break was compared with their performance after the break. The results showed that MLB relief pitchers with more than 60 innings pitched in a season may be overused. Their performance was significantly worse in the following 2 years, including innings pitched, earned run average (ERA), strikeouts per 9 innings (K/9), bases on balls per 9 innings (BB/9), walks plus hits divided by innings pitched (WHIP), fielding independent pitching (FIP), relief earned run average (RERA), and component earned run average (CERA). However, certain relief pitchers did show the ability to pitch more innings while maintain their dominance as their K/9 and BB/9 remained stable. In CPBL, the overused consequence occurred when pitching over 80 innings in one season. The number of innings pitched was significantly less in the following 2 years. MLB pitchers with more than 25 innings pitched before the All-Star break showed significant decline in performance in all categories except K/9 and BB/9 after the break. Therefore, overused consequence may occur after pitching more than 25 innings in a half season. This study indicated that professional teams should use relief pitchers with the similar degree of caution as they do with starting pitchers. The number of innings pitched should be clearly monitored to prevent the potential performance decline or injury.
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