Question: What position did this athlete play who played for the Dallas Cowboys between 1998 and 2001 and suffered a shoulder injury before the 1999 San Diego Chargers season?

Context paragraphs:
Steve Hendrickson: Steven Daniel Hendrickson (born August 30, 1966) is a former professional American football linebacker in the National Football League.  Hendrickson attended Napa High School where he was an outstanding varsity player during all four years at the school.  His #30 jersey remains the only one ever retired by the school.  He played college football for the California Golden Bears at California where he graduated with a major in history.  He was named defensive player of the game at the 1988 Blue-Gray Football Classic and was drafted in the sixth round of the 1989 NFL Draft by the San Francisco 49ers.  He played seven NFL seasons for the San Francisco 49ers, Dallas Cowboys, San Diego Chargers, Houston Oilers and Philadelphia Eagles.  Hendrickson was a member of the San Francisco 49ers when they won their fourth Super Bowl XXIV on January 28, 1990.  During his professional career, he played various positions despite his relatively small stature.  Hendrickson is fondly remembered among Chargers fans for being used as a short yardage, goal line running back, despite the fact that his main position was a defensive one.  In particular, Hendrickson scored on a 1-yard run against the Kansas City Chiefs in a January 1993 playoff game in San Diego, to cap off a 17-0 shutout of the Chiefs.

Norv Turner: Norval Eugene Turner (born May 17, 1952) is an American football coach who was last the offensive coordinator for the Minnesota Vikings of the National Football League (NFL) before resigning on November 2, 2016.  Turner has also served as offensive coordinator for the San Diego Chargers, Miami Dolphins, San Francisco 49ers, Cleveland Browns and the Dallas Cowboys, where he won two Super Bowls, both over the Buffalo Bills.  He has served as head coach of the Washington Redskins, Oakland Raiders, and San Diego Chargers.  He is the older brother of Ron Turner, the former head coach at the University of Illinois and a former Chicago Bears offensive coordinator.

1999 San Diego Chargers season: The 1999 San Diego Chargers season began with the team trying to improve on their 5–11 record in 1998.  It was Mike Riley's first season as the team's head coach.  Before the season, Ryan Leaf wound up suffering a shoulder injury during the Chargers' first training camp and was lost for the season.  Following a 4-1 start, the team suffered six straight losses before winning four of their final five games to finish 8-8.

1972 San Diego Chargers season: The 1972 San Diego Chargers season began with the team trying to improve on their 6–8 record in 1971.  The Chargers would not get off to a good start, as they were devoured 34-3 in their season opener at San Francisco.  After their week 2 win against the Denver Broncos, the Chargers would play to a 17-17 draw with another cross state rival, the Oakland Raiders.  It was San Diego's fourth tie in 3 seasons (they tied 3 times in 1970).  Even after they defeated the Baltimore Colts in the week following the tie, the Bolts would stumble the rest of the year, winning only 2 more games en route to a 4-9-1 season.

Ryan Leaf: Ryan David Leaf (born May 15, 1976) is a former American football player who was a quarterback in the National Football League (NFL) for four seasons.  He played for the San Diego Chargers and the Dallas Cowboys between 1998 and 2001, and also spent time with the Tampa Bay Buccaneers and the Seattle Seahawks.

Marcellus Wiley: Marcellus Vernon Wiley Sr. (born November 30, 1974) is a retired American football defensive end who played 10 seasons in the National Football League for four different teams.  He was selected with the 22nd pick of the second round of the 1997 NFL Draft out of Columbia University by the Buffalo Bills.  After four seasons with the Bills, he played for the San Diego Chargers, Dallas Cowboys and Jacksonville Jaguars.  He was selected to the AFC Pro Bowl team in 2001, as a member of the San Diego Chargers.

1961 San Diego Chargers season: The 1961 San Diego Chargers season was the team's second in the American Football League.  It was the Chargers' first season in San Diego, where the team remained until 2017.  The Chargers won their first eleven games and clinched the Western Division by mid-November, but only managed one victory in December.  Like the previous season, the Chargers' season ended with a loss to the Houston Oilers in the AFL championship game, this time 10–3 at Balboa Stadium in San Diego.

Brian Roche: Brian Roche (born May 5, 1973) is a former American football tight end in the National Football League for the San Diego Chargers, Kansas City Chiefs, and Dallas Cowboys after having been drafted as the 81st overall draft pick by the San Diego Chargers in the 1996 NFL Draft.  He was a former AP and Football News All American at San Jose State with 68 catches and 729 yards his Senior Year.  He played in the East-West Shrine Game and Hula Bowl All Star Games after his senior season as well as attended the NFL Scouting Combine in Indianapolis, Indiana.

Tony Berti: Charles Anton Berti, Jr. (born June 21, 1972, in Rock Springs, Wyoming) is a former professional American football player who played offensive lineman for four seasons for the San Diego Chargers.  Starting at guard and tackle in 1996 and 1997, Tony was an integral member of the Chargers' offensive line.  A shoulder injury during training camp in 1998, put Tony on the IR list for most of the season.  With a significant number of starters injured and limited maneuverability under the salary cap, the Chargers reluctantly traded Tony to the play-off bound Seattle Seahawks with only five weeks remaining in the season.  In 1999, Tony was one of only two free-agents signed by the two-time Super Bowl champion Denver Broncos.  However, another shoulder injury and subsequent surgery during training camp sidelined him again for the 1999 season.  Tony signed with the Green Bay Packers in 2000.  Days into training camp he abruptly announced his retirement.

2013 San Diego Chargers season: The San Diego Chargers season was the franchise's 44th season in the National Football League (NFL), the 54th overall, and the 1st under head coach Mike McCoy.  The Chargers finished the regular season with a record of 9–7, improving on their 7–9 record from 2012.  Also, they qualified for the playoffs for the first time since 2009.  The Chargers defeated the Cincinnati Bengals in the Wild Card round by a score of 27–10, but lost to the Denver Broncos in the Divisional round by a score of 24–17.  As of 2016, this is the most recent time the Chargers have qualified for the playoffs.  This would turn out to be the Chargers final playoff appearance in San Diego.

Supporting paragraphs: 1999 San Diego Chargers season Ryan Leaf
Answer: quarterback