Ron Roberts doesn’t have to worry about having Auburn’s defense ready to play for another five months. That’s good, because for as “outstanding” as he said his first spring as the Tigers’ new defensive coordinator has been, the unit still has work to be done to get to a spot where Roberts is comfortable, at least from a numbers standpoint.

As Auburn winds down spring practice, with the A-Day game just 10 days away, Roberts said he has about 16 or 17 players he believes can be relied on to contribute for the defense. The number he wants by the end of fall camp is closer to 25.

“What I really want to see for the remainder of spring is having more guys get in the can-do category,” Roberts said. “…We’ve got to get more guys to the boat that can be functional when we get on the field, to execute the scheme and know what we’re trying to get done and be able to do that.”

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To get to that 25-player threshold, Roberts wants Auburn to be able to go three-deep along its three-man defensive line (nine players) and at inside linebacker (six players), plus at least a couple reliable Jack linebackers while rounding out that number with defensive backs.

Through 10 spring practices, Roberts is feeling pretty good about the inside linebacker group, believing the Tigers currently have five they can count on to contribute this fall. Ole Miss transfer Austin Keys has been running with the first team alongside senior Wesley Steiner, while Cam Riley and Robert Woodyard Jr. have been the second pairing. LSU transfer Demario Tolan and former North Carolina transfer Eugene Asante appear to be the next two vying for spots in the rotation.

Along the defensive line, Roberts believes Auburn has six or seven players who are ready to go at this point. The first grouping during Monday’s practice included Marcus Harris at end, Jayson Jones at nose tackle and Kentucky transfer Justin Rogers at defensive tackle. The second unit saw Jeffrey M’ba at end, Purdue transfer Lawrence Johnson at nose and Maryland transfer Mosiah Nasili-Kite at tackle. The first two Jack linebackers in the rotation were Vanderbilt transfer Elijah McAllister and freshman standout Keldric Faulk.

The secondary is where Roberts expressed more concern about numbers, even as that unit is largely viewed as the strength of the Tigers’ defense heading into this season.

“Really, I’m going to be honest with you, we don’t have a lot of depth in the secondary,” Roberts said. “That’s probably the biggest one right now.”

Auburn returns several key pieces to its secondary from last season, including its top-two corners in Nehemiah Pritchett and D.J. James, safeties Zion Puckett and Jaylin Simpson, and star/nickels Keionte Scott and Donovan Kaufman. For all that returning experience, though, Auburn doesn’t quite have a functional two-deep on the back end of its defense yet, according to Roberts.

That’s in part because of injuries. Sophomore J.D. Rhym, for instance, is out for the remainder of spring with an injury, leaving Auburn with just three available scholarship corners at this point: Pritchett, James and freshman standout Kayin Lee. That trio will be part of the equation come fall, when Auburn will also add reinforcements, both from a health standpoint and a group of incoming freshmen.

Auburn also has “some youth” at safety behind the top-two of Puckett and Simpson, and Roberts wants to see more progress there to feel comfortable with the depth heading into the season.

Getting to that solid 25-man rotation on defense is a process, as Roberts and his staff evaluate and grade each position daily based on alignment, assignment, technique and ability to get the job done. That process takes time, and it will not only include the final five practices of spring, but it will also continue into summer workouts and the duration of fall camp.

Fortunately for Roberts and the rest of the defensive staff, time is on their side — for now — as they try to identify the remaining nine or so players who can develop into contributors, whether it’s as core rotation pieces, players who can give them 10 snaps a game at a position or someone who can step up in the even of an injury “without taking a major drop-off.”

“That’s the biggest thing,” Roberts said. “We talk about getting in that category: There’s a certain level of play of alignment, assignment, technique and production that you show up with that you have to meet in order to step on a football field. So, I think there’s still some guys that — we call them, they’re in the gray category, which is a question mark — and we’ve still got some growth to go with them.”

Tom Green is an Auburn beat reporter for Alabama Media Group. Follow him on Twitter @Tomas_Verde.