Provo — Two of the most prolific offensive players in school history —Taysom Hill and Jamaal Williams — have finally left the BYU football program. The quarterback and running back, coincidentally, begin another training camp together again with the Green Bay Packers on Thursday — Hill as an undrafted free agent and Williams as a fourth-round draft pick who signed a four-year contract worth nearly $3 million in May.

The Cougars also begin training camp for the 2017 season on Thursday afternoon. How well their offense replaces Hill, Williams and their top three receivers from 2016 — Nick Kurtz, Colby Pearson and Mitch Juergens — will go a long way in determining whether coach Kalani Sitake’s second season is as successful as his first.

“We’ve got some great players to replace on offense, no question about that,” second-year offensive coordinator Ty Detmer said in June. “But I think we will be fine there. The talent is there, and we’ve got four starters back on the offensive line. We should be able to pick up where we left off last year, although we may have to move the ball in a different way.”

In other words, look for the Cougars to throw the ball more. No surprise there.

Speaking of 2016, BYU went 9-4 after Bronco Mendenhall bolted for Virginia, losing those four games by a total of eight points and eking past Wyoming 24-21 in the now-defunct Poinsettia Bowl.

July 26 (when players reported for camp) is one of the earliest starts ever at BYU because the Cougars open the season on Aug. 26 against Portland State, having shrewdly added the game against a Football Championship Subdivision foe last December as a way to prepare for a killer September schedule that includes LSU, Utah, Wisconsin and Utah State before an early October game against Boise State and successive trips to Mississippi State and East Carolina.

Of course, the cupboard is far from bare at the quarterback position. Junior Tanner Mangum is the clear-cut starter, having started in 12 games as a freshman in 2015 when Hill suffered a season-ending Lisfranc injury in the opener. Mangum set BYU freshman records with 3,377 passing yards and 23 touchdowns two years ago, then completed just 22 of 33 passes last year for 241 yards and three touchdowns last fall, most of those in the bowl game.

It is Mangum’s time to lead, and shine, and he knows it.

“This season is a big season for our program, and we have some big goals for ourselves,” Mangum said.

There are very few questions on special teams as all the kickers, punters, deep snappers and return specialists return for ST guru Ed Lamb. They will need to find a new place-holder.

Key playmakers such as safety Micah Hannemann, cornerbacks Dayan Ghanwoloku (Lake) and Troy Warner and linebackers Fred Warner, Butch Pau’u and Francis Bernard return on defense. Finding an adequate replacement for ballhawking safety Kai Nacua will be second-year defensive coordinator Ilaisa Tuiaki’s primary concern, along with developing a relatively inexperienced defensive line that welcomes the return of outstanding pass rusher Sione Takitaki, forced to miss the 2016 season for undisclosed reasons.

Defensive linemen Tomasi Laulile and Moses Kaumatule had eligibility remaining but will not return.

Led by All-America candidate Tejan Koroma at center, the offensive line should be solid. Tuni Kanuch, Keyan Norman and and Thomas Shoaf are also back for a unit that has 84 combined returning career starts.

The big questions, then, are at the offensive skills positions — receiver, running back and tight end. The Cougars return only 18.4 percent of their rushing yards, 9.4 percent of their passing yards and 43.9 percent of their receiving yards — or 14.9 percent of their total offense — from 2016.

Junior Squally Canada is the heir apparent to the bulk of Williams’ carries, having rushed 74 times for 315 yards last year, but the RBs room is full with Wisconsin transfer Ula Tolutau, converted linebacker Kavika Fonua, returnee KJ Hall and 2016 redshirts Trey Dye and Riley Burt also pushing for carries.

At receiver, returnees Jonah Trinnaman ( ), Talon Shumway and Aleva Hifo are listed as the starters, but Detmer and Sitake are counting on big contributions from two guys who redshirted last year, Akile Davis and Micah Simon.

Moroni Laulu-Pututau has moved from receiver to tight end and will work with Tanner Balderree and promising freshman returned missionary Matt Bushman to bring that position back to prominence.

“Right now, I can tell you, we are not lacking in talent in a lot of places,” Sitake said.

We are maybe lacking some depth in places, but for the most part, the talent is there. They just need to compete. We’ve got some guys who redshirted last year who are going to surprise some people.”