[1][2] Injuries prevented him from achieving a high standard in the 2012 indoor season, but outdoors he returned to form with a Big Ten Conference long jump win in a new best of 7.96 m (26 ft 1+1⁄4 in).

[5] In his final collegiate competition he had his first and only podium finish at the 2013 NCAA Division I Outdoor Track and Field Championships, ending the long jump contest in third place.

[7] Signing a contract with adidas, Hartfield established himself among the nation's top professional athletes with a third-place finish at the 2014 USA Outdoor Track and Field Championships, recording a mark of 8.03 m (26 ft 4 in).

He equalled his best for second at the Gugl Games and had his best performance on the 2014 IAAF Diamond League at the season-ending Memorial Van Damme meet, placing fourth with a jump of 8.03 m (26 ft 4 in).

[2] He skipped the 2015 indoor season and began outdoors with the biggest win of his career at that point, clearing 8.27 m (27 ft 1+1⁄2 in) to defeat training partner Jeff Henderson to the top of the podium at the IAAF World Challenge Beijing meet.

[9] Turning to the 2015 IAAF Diamond League circuit, he was beaten only by Olympic champion Greg Rutherford at the British Grand Prix in Birmingham and also the Bislett Games in Oslo.

[10][11] At the 2015 USA Outdoor Track and Field Championships he had the longest jump of his career at 8.42 m (27 ft 7+1⁄4 in), assisted by a strong wind, and returned to the third national spot behind Marquis Dendy and Henderson.