“Next man up!”

It’s the timeless mantra preached by football coaches everywhere about the need to always keep moving forward even in the wake of injuries with the next guy in line stepping up to do the same job.

It sounds great and is a fine motivational ploy, but it isn’t always grounded in reality. The stark truth is that some injuries are more devastating than others and take time from which a team can recover, if at all.

The month of August is always littered with injury news, and coaches subsequently talking “Next man up!”

If only it were that easy.

Here’s a look at some of the key injuries around the SEC and how it’s going to affect their teams as the regular season inches ever closer.

Arkansas RB Jonathan Williams: The senior NFL prospect is lost for the regular season after the school announced that he would need corrective surgery for a left foot injury. The loss of a second-team All-SEC pick who rushed for 1,190 yards and 12 touchdowns last year can’t be underestimated, but the Razorbacks, who were blessed to have two 1,000-yard rushers in 2014, are perhaps one of the few teams capable of withstanding such a blow. Alex Collins figures to handle the bulk of the running chores after himself chewing up 1,100 yards and 12 touchdowns in 2014. He’ll have plenty of help from bruising 256-pounder Kody Walker and freshman speedster Rawleigh Williams III in a deep Arkansas running back stable.

Tennessee OG Marcus Jackson: Jackson likely will miss the entire season after recently suffering a biceps injury during a blocking drill on Aug. 10. A starter for 12 games last year, the fifth-year senior was the most experienced returnee on a Vols offensive line that struggled mightily in 2014. Brett Kendrick, who exited the spring at right tackle, will assume Jackson’s vacated spot. Jackson earned Freshman All-American honors after playing in every game and starting five in 2011 and was expected to have been a key cog up front this year.

Vanderbilt WR C.J. Duncan: The versatile redshirt sophomore was lost for the season after suffering a lower leg injury during practice on Aug. 12. Duncan started nine games in 2014, finishing the season as the team’s third-leading receiver with 28 catches. His four touchdown receptions matched a team-high. His loss is a devastating one to an already offensive-challenged Commodores team that in 2014 ranked last in the SEC in scoring offense and failed to win a conference game. New offensive coordinator Andy Ludwig had planned to employ Duncan, a former high school quarterback, as a “hybrid playmaker” who would line up in the backfield on occasion.

Vanderbilt OT Andrew Jelks: A two-year starter at left tackle and legitimate NFL prospect, Jelks suffered a knee injury in practice last week and will miss the entire season. The junior had started 21 consecutive games, 12 at left tackle and nine at right tackle. The loss was yet another major blow to the Commodores, who especially lack depth at the tackle spot.

LSU S Jalen Mills: The senior safety is expected to miss as much as six weeks after suffering what the New Orleans Times-Picayune reported to be a fractured fibula in practice on Aug. 19. Mills has started all 39 games in which he’s played for the Tigers, both at corner and then at safety and toyed with the idea of jumping to the NFL before returning to Baton Rouge. The Tigers, however, are loaded as always in talent on defense and have plenty of quality options when looking for a replacement. It was Mills, after all, who more than ably filled in for former Heisman Trophy finalist Tyrann Mathieu when the Honey Badger was dismissed from the team in August 2012.

Florida LB Antonio Morrison: Last year’s second-team All-SEC pick remains out after undergoing two offseason knee surgeries to repair the injury he suffered in last year’s Birmingham Bowl, but Gators coach Jim McElwain and his staff remain optimistic about his recovery. Morrison, who led the team with 101 tackles a year ago, could be back in the lineup at middle linebacker before Florida gets into the meat of its schedule in October. Junior Alex Anzalone Jr. will man Morrison’s spot until he returns.

Tennessee OG Austin Sanders: The redshirt sophomore will miss the entire 2015 season after suffering a biceps injury less than two weeks after teammate Marcus Jackson went down with a similar injury. Sanders appeared in five games last year and took reps with the first-team offense this spring with Jackson out. The losses of Jackson and Sanders leave coach Butch Jones and his staff suddenly scrambling to find cohesive combinations for an offensive line that surrendered an SEC-high 43 sacks in 2014.

Tennessee CB Rashaan Gaulden: The sophomore will miss the entire season after suffering a fractured foot in practice on Aug. 20. Gaulden had been slated to be the Volunteers’ primary nickelback, meaning defensive coordinator John Jancek will have to look elsewhere for another ball-hawking body to plug in the secondary for his team’s five defensive backs packages. Sophomore Justin Martin is a likely replacement, but he’s been slowed by a sprained knee and missed parts of preseason camp. Gaulden played in 11 games as a freshman last year, making his biggest impact on special teams. His loss will be felt by a Tennessee defense that often employs its nickel packages to counter opposing spread offenses.

Georgia WR Justin Scott-Wesley: The senior’s playing days may be finished after he suffered his third knee injury in less than two years during practice on Aug. 17. Scott-Wesley appeared destined for stardom in 2013, but tore the ACL in his right knee. He appeared in just six games in 2014 while mending from an ankle injury, but looked healthy again this spring. Scott-Wesley underwent arthroscopic surgery for a torn meniscus in his right knee in July before hurting the joint again in practice. His former high school coach says Scott-Wesley is “done playing.”

Florida OT Martez Ivey: The former five-star recruit had been working with the Gators first-team offense at right tackle, only to undergo arthroscopic surgery on Aug. 27 to correct a lingering leg injury that had followed him since high school. There is no timetable for his return, but the injury is not expected to be a season-ending one. Ivey’s loss, however, comes as a blow for a Florida offensive line that already lacked both depth and experience. Ivey had quickly proven himself as good advertised. His sudden absence means the Gators coaching staff must again shift players around to find the best unit to put out on the field for the Sept. 5 season opener against New Mexico State.