Cooper, who missed all of 2015 after Tommy John surgery, was 6-3 with a 2.32 ERA in 16 games for Texas in 2017, including 15 starts, with 110 strikeouts and 33 walks in 89⅓ innings.
"Cooper has maintained steady stock as a late second or third round pick all spring but he could go as high as the supplemental round due to his relative lack of leverage and his status as an advanced college arm," wrote John Sickels at Minor League Ball. "He could reach the majors fairly quickly."
From the MLB Pipeline scouting report:
At his best, Cooper can deal at 92-94 mph and reach 96 with his fastball. He uses his size and an overhand delivery to generate steep downhill plane, helping his heater induce swings and misses as well as groundballs. He still has to prove he can maintain his velocity over a full schedule because it has dipped in the second half of the last two college seasons.
Cooper was drafted as a redshirt sophomore in 2016 in the 34th round by the Nationals, but did not sign.
The No. 62 overall pick comes with a slot value of $1,018,200.