Mayock said on NFL Network's "Path to the Draft" on Wednesday, "If I'm a general manager I'm not taking him in the first round, and I might not take him in the second round."
Mayock previewed his top-100 draft prospect list, and while the entire list has yet to be released, Coples was revealed as the No. 50-rated prospect. Other prospects' placement was also announced, such as Boston College LB Luke Kuechly (No. 6) and Alabama safety Mark Barron (No. 9).
Mayock acknowledged Coples' talent -- he is the top-rated defensive end in Mayock's prospect rankings -- as well as Coples' value in the league as a pass rusher, but there's a huge caveat.
"To me, the bust potential is high, and the earlier you take him the more risk there is inherent in that," Mayock said. "So, for me, Quinton Coples is not even a draftable player."
While the review of Coples was less than flattering, a number of prospects were acknowledged for their recent rise up draft boards.
The report on Kuechly was glowing. "I've had several general managers tell me he's the single cleanest player in the draft," Mayock said. "I think he's the best pure zone-drop pass linebacker I've ever seen on tape."
Huge production in a BCS conference, no off-the-field issues and a lack of medical concerns all help Kuechly's cause, as does his versatility. "What usually knocks linebackers down is their inability to stay on the field for three plays. It's the opposite with Kuechly," Mayock said.
Mayock projects the Boston College product to be drafted anywhere between No. 12 (a pick held by the Seattle Seahawks) and No. 20 (Tennessee Titans). Another player Mayock figures to be in that selection range is Barron, who Mayock projects to go as early as No. 14 to the Dallas Cowboys or No. 20 to the Titans.
While he didn't reveal their positions in his top-100 rankings, Mayock did point out two prospects with rising draft stock: Syracuse defensive end Chandler Jones and Boise State outside linebacker Shea McClellin.
"Awareness of how good of a football player (Jones) is is permeating throughout the league right now," Mayock said. "He's stout against the run, and he's scheme-diverse. The 3-4 teams look at him as either a defensive end or an outside linebacker. The 4-3 teams love him as a base end."
McClellin has recently been lifted into the first-round projections of NFL.com mock drafts. Brian Baldinger has McClellin going No. 28 to the Green Bay Packers, while Albert Breer sees McClellin going No. 31 to the New England Patriots.
"The more tape you watch, the more appreciation you have for this (McClellin) kid. He makes plays in every single game I watch," Mayock said. "I think people are starting to wake up to McClellin. For instance, if you're sitting there at No. 20 and you're the Tennessee Titans, and Quinton Coples is there versus Shea McClellin versus Chandler Jones versus Whitney Mercilus, I wouldn't touch Quinton Coples. I'd look at those other guys first."
Michigan State's Jerel Worthy is Mayock's second-rated defensive tackle and ranks in the top 20 among Mayock's top-100 prospects. Worthy is rated below Mississippi State's Fletcher Cox, but ahead of Memphis' Dontari Poe and LSU's Michael Brockers. Worthy's performance in two key Big Ten games impressed Mayock.
"The first two tapes I watched were Iowa and Wisconsin -- two excellent offensive lines -- I thought he was dominant in both games," Mayock said while also acknowledging that Worthy has mid-first round value.