Now Knight, the Sooners starting quarterback, is left with junior Sterling Shepard as his lone proven receiver to target heading into this season. Shepard had 51 receptions for 603 yards and seven touchdowns a year ago. The rest of the receivers on the Sooners' roster combined for 17 receptions for 228 yards in 2013.
The Sooners were hoping Green-Beckham would become eligible to provide a proven playmaker on the outside after the 6-foot-6, 225 pound receiver had 59 receptions for 883 yards and 12 touchdowns for Missouri in 2013 before his dismissal last spring.
The Sooners will have to be without receiver Dorial Green-Beckham for the season.
Instead, Shepard will enter the season as Knight's No. 1 target and the clear focus of opposing secondaries. It's an unproven but talented group of receivers that will have to step up if the Sooners hope to earn a spot in the College Football Playoff this fall.
Much of the burden is likely to fall upon Durron Neal, the second-leading returning receiver on the roster. Neal was an Army All-American when he arrived on campus but has yet to fulfill those high expectations with 18 career receptions for 251 yards in his first two seasons.
"I think we have some real stability with Shepard and Neal on the perimeter," receivers coach Jay Norvell said earlier this week. "Then we've got some young guys, K.J. Young and Michiah Quick, that are kind of coming on in the slot."
Sophomore Derrick Woods is another receiver the Sooners are counting on to become an impact player on offense for the first time in his career after a redshirt freshman season that featured just two receptions for 29 yards including a clutch third-down reception in the Allstate Sugar Bowl.
"We could play with Derrick Woods as a starter," Norvell said. "There's no question and feel confident doing that. He's been in the fire. He made a huge play in the Sugar Bowl and the one thing about that kid, you get him in a competitive situation, he really responds."
A portion of the onus could also fall upon covered tight end Blake Bell, who made the switch from quarterback in January with an eye on becoming an big target for Knight.
Keep an eye on a pair of redshirt freshmen who will get more opportunities with Green-Beckham out of the equation. Jordan Smallwood, who has impressed since he arrived on campus in the summer of 2013 but was forced into a redshirt season by a broken foot in the preseason a year ago, and K.J. Young, who has emerged as an potential impact player in the slot for the Sooners, have both used a redshirt year in 2013 to put themselves in position to make an impact this fall.
"K.J.'s just playing a lot faster," Norvell said. "He really has an understanding of what we want him to do inside. He's playing really fast, roaring off the football. That's a big thing here at Oklahoma. We really stress coming off the ball and playing with speed, and when you watch guys like Kenny Stills and Jalen Saunders, when those guys played, they roared off the football, and K.J.'s starting to get that."
Incoming freshman Michiah Quick is another player who could see his role expand with Shepard's ability to play in the slot or on the outside allowing the Sooners to move Shepard around with a goal of getting their top three or four receivers on the field.
It's clear the Sooners like their talent at receiver but it is largely unproven. OU's season opener against Louisiana Tech on Aug. 30 and second-non conference game against Tulsa on Sept. 6 will be critical for the Sooners offense to figure out which receivers can be counted on heading into their home matchup with Tennessee on Sept. 13.