It was almost noon on Tuesday, and all but two Jaguars' players had left the practice field. The rest were back inside the air-conditioned TIAA Bank Field facility.
As the heat index was hitting triple digits outside, class remained in session in stifling humidity for the team's longest-tenured NFL player and its most promising rookie.
Calais Campbell, the 32-year-old football professor, had stayed behind for a tutoring session, giving pass-rushing tips and other pointers to defensive end Josh Allen.
"He's just showing me a couple more moves I can have in my toolbox," said Allen, the team's first-round draft pick. "I thank him for that because he doesn't have to do it."
"Like in school, just staying after to earn some extra credit," Campbell added as the pair walked off the field.
Don't dismiss that as a token gesture. It not only uplifts Jaguars' coaches to see the way a veteran like Campbell tries to make teammates better, but it's a small glimpse as to why this defensive line has the potential to be the NFL's best in 2019.
The talent is self-explanatory. What also matters is this group, some of whom rested in Thursday's preseason game against the Philadelphia Eagles, feels connected and supremely motivated.
Frankly, there's plenty of reason to believe this Jaguars' defense can return to 2017 form when it was a league-wide terror, starting with a D-line that has its own regrets about how last year's 5-11 record went down.
Things were hashed out the first day the team reported back for offseason workouts in mid-April. Defensive tackle Abry Jones and Campbell got their position group assembled for a heart-to-heart, clear-the-air session about not letting 2018 carry over into this year.
"Calais asked if there was anything we needed to get better at, and we just all gave our input," Jones said. "Last year ate at us because we all knew our talent, but we really underachieved.
"This year, we're all OK with keeping each other accountable. No one takes criticism personally. We sat down as a D-line and talked about things we're going to change and communication was one of the biggest things."
Campbell, who led the Jaguars with 10.5 sacks last year and made a second consecutive Pro Bowl, doesn't absolve himself from blame for the Jaguars' regression.
"One of the biggest things, to be honest, was we got a little too aggressive in trying to just get sacks and we didn't play the run as well as we could have at times," Campbell said. "I was a big culprit early in the season."
Specifically, Campbell cited a first-down play late in the Week 3 home loss to the Tennessee Titans when he thought quarterback Marcus Mariota was running a bootleg, only to see him hand off to Derrick Henry for a 5-yard gain. That fourth-quarter play was part of the Titans' game-winning drive that led to Ryan Succop's 28-yard field goal in a 9-6 Jaguars' defeat.
Looking back on it, Campbell said his mistake was "I got to trust my keys. The general rule when you're taking a chance and you read something is to make sure the ball doesn't hit your gap."
Undoubtedly, those kind of little mistakes that sabotaged the 2018 season do provide motivational fuel. But what really sets up the D-line for a bounce-back year is the group's makeup and some planet-aligning circumstances.
While it lost tackle Malik Jackson to free agency, an unexpected boost came when a promising edge rusher in Allen became available with the No. 7 draft pick. Plus, the belief is that tackle Taven Bryan will take a significant jump after a disappointing rookie season.