[5] In April 2015, Cook made it into the Shell Houston Open through the Monday qualifier, finding himself in contention in short order.

With a 4-under-par 68 on Thursday, Cook made a strong close on Friday, with four consecutive birdies to win a spot in the final group along with Andrew Putnam and Phil Mickelson.

[6] On Saturday of the tournament, Golfweek said Cook "did not fold under the pressure of playing alongside Phil Mickelson," and carded a 2-under 70 as he headed into Sunday's final round one off of Jordan Spieth's lead,[7] tied for second place at 203 with first-round leader Scott Piercy and Johnson Wagner.

On the final day, Cook finished at −10 and tied for 11th, one position short of automatic entry into the Zurich Classic of New Orleans, the next full-field PGA Tour event.

[9][10] He ended the Finals 51st among players who had not earned their cards through the regular season, one place short of full Web.com Tour status and avoiding Q School.