Everything finally fell into place for Washington State last season. The Cougars finished with nine wins for the first time since 2003. With Luke Falk at quarterback, few defenses could effectively contain Washington State's explosive passing attack. Now building a consistent winner is the task ahead for Mike Leach as 2016 approaches.

Staying competitive in the Pac-12 North may come down to what improvements Washington State can make on the defensive side of the ball. The Cougar offense, as long as Falk stays healthy, should be in good hands.

4 Storylines to Watch in Washington State’s Spring Practice

1. What can Falk do for an encore?

Many coaches have to be kicking themselves for not giving Falk a closer look when he played at Utah’s Logan High School. Falk joined Washington State program as a walk-on after receiving virtually no recruiting attention. Now he is one the Pac-12's best quarterbacks.

Related: College Football's Pre-Spring 1-128 Starting Quarterback Rankings for 2016

Falk enjoyed a breakout sophomore season last fall. He threw for 4,566 yards and 38 touchdowns while completing 69.4 percent of his passes. Falk ranked fifth nationally in total passing yards and fourth in passing touchdowns. With him at the controls, the Cougars had the nation's top passing offense (389.5 yards per game) in 2015.

There are concerns about Falk's health after he got knocked out of three different games with injuries last season and missed the Apple Cup because of a concussion. The offense's production dropped off noticeably under Peyton Bender, Falk's backup, so keeping its starting quarterback healthy is critical for Washington State's continued success.

2. Backfield blossoming

Don't look now, but Washington State is starting to get a semblance of a ground game going. Leach is notorious for having quarterbacks dial up 50 or 60 passes in a game, but he may be able to give Falk's arm a little bit of rest this fall.

The Cougars return their top three running backs — Gerard Wicks, Jamal Morrow and Keith Harrington — from a season ago. Wicks led the trio with 610 rushing yards on 5.7 yards per carry. Harrington was the top receiving threat with 312 yards on 43 catches. That group only gets deeper this spring with the addition of promising freshman James Williams.

3. Retooling the defensive line

The Cougars must find replacements for Destiny Vaeao and Darryl Paulo who can offer similar defensive playmaking skills. Vaeao was a consistent disruptor at the line of scrimmage. Paulo was a leader in tackles for a loss and sacks on the line.

Hercules Mata'afa will get a chance to move into a starting role. He did well as a pass rusher while backing up Vaeao a year ago. Robert Barber returns at nose tackle and Daniel Ekuale will slide over from tackle to play end. The trio will be counted on to boost Washington State's run defense after the team gave up nearly five yards per carry. It kept the defense on the field for long stretches and proved to be a major liability for the Cougars at times.

4. Marks headlines receivers again

Getting back Gabe Marks for one more season is an unexpected surprise. Marks seemed to be on the NFL radar at the end of last season after totaling 1,192 receiving yards and leading the Pac-12 with 15 touchdown catches.

Getting back Marks will add teeth to a receiver corps already flush with depth, talent and experience. Only Dom Williams, the No. 2 receiver behind Marks last season, is gone from Falk's top targets in 2015. It should make the unit a defensive headache again in 2016.

Washington State's Pre-Spring Outlook in the Pac-12

Leach has brought hope back to Pullman after snapping a streak of 11 consecutive losing seasons last fall. Now the task is to build on that nine-game winning season and Sun Bowl victory. The Cougars should be able to keep moving forward in the Pac-12 North. With Falk and nearly of the team's top receivers back, it's safe to say Washington State is poised to be an offensive powerhouse again in 2016.

— Written by John Coon, who is part of the Athlon Contributor Network. Coon has more than a decade of experience covering sports for different publications and outlets, including The Associated Press, Salt Lake Tribune, ESPN, Deseret News, MaxPreps, Yahoo! Sports and many others. Follow him on Twitter @johncoonsports.