Early career

Jager competed at his first USA Outdoor Track and Field Championships in the 5000 m, where he took the lead with 200 m to go before placing third behind his teammates Matt Tegenkamp and Chris Solinsky. By placing third, Jager earned the opportunity to represent the United States at the 2009 IAAF World Championships in Berlin. At the World Championships, Jager placed 11th in his heat of the 5000 m and did not advance to the final.

Much of Jager's first professional season was documented in the Runner's World web series "Wisconsin to Worlds," which followed the teammates' historic sweep at the USATF Championships and their European season as they prepared for the 2009 IAAF World Championships.^[7][8]

In early 2010, Jager experienced pain in his foot during training runs. After taking some time off, he returned to competition, but the pain persisted and culminated in a stress fracture that he received in the 1500 m final at the USATF Championships on June 25. On July 28, 2010 he had surgery to repair a fracture in the Navicular bone of his foot.

Recuperation from his surgery took time, with pool and bike workouts substituting for running. He did not do any serious running workouts until March 2011, with the remainder of that track season being an essential, gradual return to high level training rather than a season of competitive racing.

2012

In the spring of 2012, guided by coach Jerry Schumacher and former U.S. steeplechase champion Pascal Dobert, Jager switched to the 3000 m steeplechase. He made his debut at the Mt. SAC Relays in April 2012. He won that race in 8:26.14, a stunning time for a neophyte and close to the 8:23.1 Olympic A standard necessary for participation in the London Games. During this race, he also beat America's best steeplechaser at the time, Daniel Huling, now one of his training partners. Jager followed through on this auspicious performance by comfortably winning the 2012 U.S. Olympic Team Trials 3000 m steeplechase in 8:17.40.^[9][10]

On July 20, 2012, Jager broke the American record in the 3000 m steeplechase, running 8:06.81. On August 5, Jager competed in the Olympics, finishing 6th in the final. After the Olympics, on August 17, Jager ran a new personal best of 7:35 in the 3000 m at the Stockholm Diamond League meet, finishing 5th.

2013

Jager kicked off the 2013 indoor season at the Millrose Games two-mile, where he finished fourth in 8:14.95 to winner Bernard Lagat, who set the American record in that race. This made Jager the fourth fastest American indoor two-miler of all time. He was fifth in the New York Columbia Qualifier 5000 m, where he finished in a time of 13:33.37. Later on in the season he finished 2nd in the indoor mile at the Seattle Husky Classic in 3:56.14, where he got nipped at the line by his teammate, Andrew Bumbalough.

Jager raced sparingly during the outdoor season before the U.S. Championships. He ran 13:14.60 which was good for 2nd to Saucony's Ben True at the Payton Jordan Cardinal Invitational. He also placed second in the Oxy HP 1500 m in 3:36.34. At the Prefontaine Classic he placed 4th in a time of 8:08.6, only two seconds off his American record. He followed up these personal record performances with an easy win at the USATF Outdoor Championships 3000 m steeplechase, where he finished in 8:20.67, giving him the opportunity to represent the USA at the IAAF World Championships in Moscow for the second time, and also winning him his second consecutive 3000 m steeplechase national title. During his European outdoor season, he ran a 3k in Luzern which was his only race between USAs and Worlds. Jager went into Worlds wanting to improve on his 6th place in the London Olympics. He won his qualifying round of the Steeplechase in Moscow in what seemed to be an easy effort. He went on to place fifth in the final, getting out-leaned by Kenya's Paul Koech. Although he only improved one place from the 2012 Olympics, he put himself in the race and was there with 400 meters to go, with the gap to 6th place being about 3 to 4 seconds. To round out his 2013 season, he raced the 5000 m at the Brussels Diamond League Meet, lowering his personal best by 12 seconds, to 13:02.40.

2014

To kick off the 2014 outdoor season at the Prefontaine Classic, Jager ran a personal best of 3:53.33 to place him 3rd in the Men's International Mile. Only a few weeks later in Oslo, Jager was less than 2 tenths of a second off of breaking his own American 3000 m steeplechase record of 8:06.8 by running an 8:06.97. On June 29, 2014 Evan Jager won the USA 3,000 Meters Steeplechase Title by running 8:19.83.

2015

On June 27, Jager won the steeplechase at the 2015 USA Outdoor Track and Field Championships in 95 degree temperature in Eugene, Oregon. On July 4, Evan lowered the American Record in the steeplechase to 8:00.45 in 2015 Paris Meeting Areva Diamond League, despite falling over the final barrier.^[11][12][13]

Jager placed 6th in 2015 World Championships in Athletics – Men's 3000 metres steeplechase.

2016

Jager won steeplechase in a time of 8:22.48 at the 2016 United States Olympic Trials ahead of teammates Hillary Bor and Donn Cabral to qualify for the 2016 Summer Olympics.^[14]

On August 17 Jager won the silver medal at the 2016 Olympics behind Conseslus Kipruto of Kenya with a time of 8:04.28.

2017

At the 2017 World Championships in London on August 8, 2017, Evan placed 3rd in the 3000 m Steeplechase in a time of 8:15.53.^[15] The race started out slow for the first kilometer in 2:51.81, then soon after Jager took the lead and held on to it, until 300 m remaining where he was passed, first by Conseslus Kipruto (1st) and then Soufiane El Bakkali (2nd). Jager managed to hold on for third with Mahiedine Mekhissi-Benabbad close behind^[16][17]

2022

Jager suffered a stress fracture in 2018, and was unsure whether he would ever return to elite competition.^[18] But after several years, Jager returned to international competition, and placed 6th in steeplechase at the 2022 World Athletics Championships held in Eugene, Oregon.