Goodbye 105 tackles, 10 sacks and six forced fumbles.

So long 93 tackles — eight for loss — and four forced fumbles.

And sayonara, too, to 90 tackles, two sacks and nine quarterback hurries.

Those are the numbers supplied by former Kansas University linebackers James Holt, Mike Rivera and Joe Mortensen, respectively, last season — and the numbers that will have to be replaced entering 2009.

It’s no secret that the biggest challenge facing KU defensive coordinator Clint Bowen this fall will be figuring out how to duplicate that kind of production at the linebacker position.

What’s less clear, however, is who he intends to do that with.

Although the Jayhawks will have to fill just two of the linebacker spots — the team plans to operate out of a 4-2-5 alignment, using an extra safety playing a hybrid-type role — experienced talent isn’t necessarily abundant. Justin Springer, a junior from Los Fresnos, Texas, showed flashes as a reserve last fall, before suffering a season-ending injury against Kansas State. He’ll be joined by fellow ’08 reserve Arist Wright, who started two games last season and finished the year with 33 tackles. Kansas also could get a boost from running back-turned-linebacker Angus Quigley and junior college transfer Vernon Brooks, who earned JUCO All-American honors last year at Brenham (Texas) Blinn Community College.

For their part, the unit’s departing players seem confident that their replacements — whoever they turn out to be — will have little trouble making the transition to the starting lineup while anchoring a KU defense that finished 10th in the Big 12 in pass defense a season ago.

“All … of those guys can play,” Rivera said at the end of last season. “They know what it takes. They’ve seen how hard you have to work, and, hopefully, we’ve taught them a lot.”

With the exception of the linebacking corps, however, the Jayhawks appear to be in relatively good shape defensively.

The secondary, which underwent a massive midseason overhaul in ’08, returns four starters in safeties Darrell Stuckey and Phillip Strozier and cornerbacks Justin Thornton and Daymond Patterson, and the defensive line, with Jake Laptad and transfer Quintin Woods at the end positions, should provide Kansas with an improved pass-rush.

Kansas showed a marked ability to stop the run last season, allowing just 123.1 yards per game to finish 28th nationally. If the defense can maintain that level of success, while getting a boost from what figures to be a more experienced secondary, it would go a long way in the team’s quest for a first-ever berth in the Big 12 Championship.