After seven years of trying to piece back together a career that once seemed destined for greatness, Mark Prior has finally retired at the age of 33. The ex-Cubs star but hasn't pitched in the majors since 2006 but may pursue a front-office job with his hometown San Diego Padres.
Prior was in many ways the Stephen Strasburg of his day, a can't-miss pitcher with a devastating arsenal and a massive amount of hype. He was drafted 43rd overall by the Yankees in 1998 but elected to attend the University of Southern California instead. Prior went second in the 2001 draft to the Cubs because the Twins had the first pick and opted, not without some controversy, to take hometown high-school catching prospect Joe Mauer.
Considered one of the best pitching prospects ever and possessed of supposedly perfect mechanics, Prior was given a $4 million signing bonus plus a major league contract worth $10.5 million over five years that put him directly on Chicago's 40-man roster. He made his professional debut in Double A in 2002 at the age of 21 and made just nine starts in the minors (going 5-2 with a 2.29 ERA) before making his major league debut on May 22 of that year and striking out 10 Pirates while allowing just two runs in six innings. Prior remained in the Cubs' rotation for the remainder of the year, striking out 11.3 men per nine innings, including 10 or more in six of his 19 starts, while posting a 3.32 ERA (122 ERA+).
The next year, the 22-year-old Prior emerged as the ace he was expected to be. He went 18-6 with a 2.43 ERA (179 ERA+), 245 strikeouts (10.4 per nine innings) and a 4.90 strikeout-to-walk ratio, making the All-Star team and finishing third in the Cy Young voting and ninth in the MVP voting. Behind the young pitching triumvirate of Prior, Kerry Wood and Carlos Zambrano, the Cubs won their division for the first time since 1989 and won their first post-season series since 1908 by beating the Braves in the Division Series with Prior throwing a complete game to beat Greg Maddux in Game 3.
Chicago then jumped out to a 3-games-to-1 lead on the Marlins in the National League Championship Series, with Prior turning in another strong outing to win Game 2. The Cubs' season fell apart in their infamous Game 6 loss, in which Prior was on the mound in the eighth inning with a 3-0 lead only to succumb to the confluence of Steve Bartman, Alex Gonzalez and Dusty Baker -- to say nothing of the Marlins themselves -- that derailed the Cubbies' shot at their first pennant since 1945.
Including the postseason, the 22-year-old Prior threw 234 2/3 innings in 2003, that despite spending the second-half of July on the disabled list due to shoulder soreness. On the season, he threw more than 120 pitches in a game 10 times and more than 130 four times. From his first start in September through his complete game against the Braves in the Division Series, his pitch counts were 131, 129, 109, 124, 131, 133, 133. After that season, he was never the same.
Prior's 2004 season didn't start until June because of an ankle injury, and after his return, his walk and home run rates spiked, pushing his ERA up to 4.02. Those rates remained high in 2005, a season that also started late, this time due to elbow inflammation. A comebacker broke his pitching elbow in late May, and he finished the season with just 166 2/3 innings pitched. He would never again qualify for an ERA title.
In 2006, Prior opened the season on the disabled list for the third straight year. This time it was his shoulder that kept him out, and it was that shoulder that would ultimately limit him to nine starts that season, his last in the major leagues. In his final start that year, on Aug. 10, Prior gave up six runs in three innings in Milwaukee and struck out just one. His shoulder put him back on the DL thereafter. The following April, he had surgery on the joint for the first time, this one to repair a torn labrum and rotator cuff. In April 2008 he had another operation to repair a torn anterior capsule and a humeral avulsion of the glenohumeral ligaments. As a result of those surgeries, Prior missed three full seasons, 2007-09.
Prior spent the latter two of those inactive seasons in San Diego's organization. Then, from 2010 to 2013 he drifted through the organizations of the Rangers, Yankees, Red Sox and Reds, managing to throw 58 2/3 minor league innings (plus some spring training frames), most of them in relief, across those four seasons. Prior struck out 86 men in those innings, but he also walked 37 (5.7 BB/9) and never managed more than 25 innings in a single season. This past season, he made it into just seven games for the Reds' Triple-A affiliate in Louisville, posting a 4.66 ERA.
Despite his abbreviated career, Prior has a significant legacy within the game. Beyond his place in the narrative of the Cubs' continued misfortunes, his injuries proved to be the flashpoint in the increased sensitivity to pitch counts around the game. The need to protect pitchers' arms from fatigue was a battle that many in the advanced analysis community were already fighting before Prior came into the league, but the confluence of his heavy workloads in 2003 and his subsequent injuries made that message sink in within the game. Perhaps there is no better measurement of the impact Prior had than this: In 2003, at age 22, Prior made four starts of 130 or more pitches in 33 total starts between the regular and postseasons. In 2013, there were just four such games in all of the major leagues in 2,469 regular and postseasons games -- none by a pitcher under the age of 25.