With each recruiting class, coaches across the SEC plan to build depth.

But injuries can still send a season through the spin cycle, especially to key players and at key positions. Coaches believe in a “next man up” mentality, but easily replacing experience and production is another matter.

Here are 10 players SEC teams can’t afford to lose in the 2017 season:

Arden Key, LSU

There’s an asterisk here given Key’s recent absence. After he was second in the SEC with 12 sacks in 11 games as a sophomore, he is widely viewed as the conference’s top returning pass-rusher. Key, a junior whom most expect to be a first-round selection in next year’s NFL Draft, took a leave of absence from the program this spring for “personal reasons,” the school announced in February.

Nick Chubb (7.06) and Johnny Manziel (7.01) are the only players in SEC history who averaged more than 7 yards per carry in a season (minimum 200 carries). Derrius Guice averaged an astounding 7.58 last year on 183 carries.

Derrius Guice, LSU

On most short lists to be in the mix for the Heisman Trophy, Guice led the SEC, even as a part-time starter last season, with 1,387 yards on just 183 carries for a 7.58 per carry average. He broke Leonard Fournette’s single-game school rushing record, too.

Christian Kirk, Texas A&M

The league’s best returning receiver and arguably most versatile player, Kirk has lined up inside, outside, returned kicks and punts. His 1,418 all-purpose yards ranked fourth in the SEC in 2016 and No. 1 among non-running backs. Expected to be a preseason All-American entering his junior year in 2017, Kirk has a chance to break the SEC all-time receptions mark in three seasons.

In his career, Kirk has 163 receptions for 1,937 yards and 16 touchdowns in only two seasons while also returning five punts for scores.

Can Minkah Fitzpatrick lead the SEC in INTs for the second consecutive year? That hasn't happened since Tennessee's Deon Grant shared the title in 1998 (with a guy named Kirby Smart) and won it in 1999.

Minkah Fitzpatrick, Alabama

One of the best defensive backs in college football, whether it be cornerback or safety, Fitzpatrick led the SEC with six interceptions last season and returned two for touchdowns. He was also picked as a first-team All American by the Associated Press and American Football Coaches Association. In his career, he’s returned four interceptions for touchdowns, a school record.

Kamryn Pettway, Auburn

Pettway’s one of those players who changes the fortunes of his team when he’s on the field and productive. Auburn is 5-0 when he rushes for more than 150 yards, and in seven SEC games last year, Pettway averaged 138.7 yards per game with seven touchdowns. He started six of 10 games and was named first team All-SEC by the coaches and AP.

Ralph Webb, Vanderbilt

Vanderbilt’s career record holder with 3,347 rushing yards, Webb went for a program-best 1,283 yards with 13 touchdowns as a junior. Most notably, he’s done it with a consecutive start streak of 37 games. The 13 TDs were the third most by a SEC player and the most by a Commodore since 2013.

Frank Ragnow, Arkansas

Ragnow didn’t allow a sack for the second consecutive season and reduced his pressures allowed from 19 in 2015 to 12. Pro Football Focus ranked him as the nation’s best offensive lineman in 2016. By starting all 13 games, Ragnow ran his starting streak to 26 consecutive games. Behind Ragnow, Arkansas running backs had nine 100-yard rushing performances and Austin Allen threw for 3,430 yards.

Credit: Denny Medley-USA TODAY Sports

Braden Smith, Auburn

Smith passed on the NFL and returns to Auburn with a chance to extend his 27-game consecutive start streak, and he’s appeared in 39 games since 2014. Looking to start his third year, but moving from right guard to right tackle, Smith last year was named All-SEC first team by AP, ESPN and Pro Football Focus.

Nick Fitzgerald, Mississippi State

Fitzgerald won the quarterback competition last season and went on to start 13 games and break nine school records. He rushed for 1,375 yards and 16 TDs. Other records included 100-yard rushing games by a quarterback as well as average yards per rush. That made him third behind Johnny Manziel and Cam Newton in single-season rushing yards by a QB in SEC history

Austin Allen, Arkansas

Arguably the best quarterback in the SEC, Allen last year was the league’s most productive passer with a league-high 3,430 yards, which was 20th in the FBS. His four 300-yard passing games in SEC play ranked second in single-season school history and tied for third all-time.