Washington State begins its third spring football session under Mike Leach on Thursday, seeking, among other things, to find answers to questions on the offensive line and defensive backfield.

The Cougars have eight starters back on offense, including quarterback Connor Halliday, and seven on defense. From their New Mexico Bowl team of last December, they lost the three starting offensive linemen from center to right tackle, and the secondary is without three primary starters, including All-American Deone Bucannon.

Leach was adamant entering 2013 fall camp that starting positions weren’t settled, so naturally that goes for this spring as well.

Asked about the general message to his team, 6-7 last season, he said, “There’s always a message. Typically, it’s linked to having a vision to your potential and the necessity of hard work to take you there.”

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Halliday is listed at 197 pounds, up from about 190, and is the presumed quarterback. But Leach says the Cougars will run two “skeletons” to maximize repetitions, and touted Tyler Bruggman will get a chance, as well as walk-on Luke Falk. Both will be redshirt freshmen in the fall.

The offensive line will undergo major change. Guard Joe Dahl and tackle Gunnar Eklund switched positions for the bowl game, and are expected to stay there. Candidates among the vacated spots include O’Dea product Sam Flor at center and Kennedy grad Cole Madison at right tackle.

“Nothing’s set,” Leach said. “The guys who started last year (Eklund and Dahl) are not set, either.”

Leach also named running back as a position of interest. Marcus Mason will be hard to unseat, but there appears to be decent depth there, and Theron West had a breakout performance in the bowl game.

In school is Texas A&M receiver transfer Sebastian LaRue, a four-star high-school recruit, whom Leach called “explosive out of his cuts.” But LaRue is yet ineligible pending an appeal that would allow him to play in 2014.

On defense, Destiny Vaeao moves from the Buck linebacker to end, which Leach called “not a dramatic change.”

There’s experience on the front seven, but the secondary needs to be rebuilt, a process that took a possible recent hit with an assault charge against rising sophomore corner Daquawn Brown.

Asked if Brown is in good standing, Leach said, “We’re going to have to wait and see how that unfolds. Most of what’s come out has been greatly embellished.”

The Cougars have to replace reliable kicker Andrew Furney and also settle on a new punter. Wes Concepcion of Kent­ridge High punted late last season and appears to lead there.

WSU’s spring game is April 26 at Albi Stadium in Spokane, with a final workout April 29.

Bud Withers: 206-464-8281

or bwithers@seattletimes.com