But it also affects their head coach, who recruited and coached them, all while also helping to develop them into good men for the rest of their lives.
"Most of the time it's emotional, from [the] beginning when I see them run out," said Coach Mendenhall about Senior Day. "Then it goes away during the game, but then the minute the game's over it starts again and it's one of the coolest days of the year."
Nineteen seniors in all will be honored on Saturday, including student assistant Steven Thomas, whose playing career as a safety ended last year following a concussion.
Like with any other team's senior class, BYU's seniors didn't all enter the program at the same time. Some redshirted along the way, some didn't. Some were transfers, while others were four-year players. But add in the unique BYU element of missions, and there is quite the wide period in which the Cougar seniors have played.
For example, while this is Hebron Fangupo's only year at BYU, Marco Thorson actually joined BYU's program back in 2005 during Mendenhall's first year as head coach. Thanks to a redshirt year and a mission along the way, the offensive lineman's BYU career is only now coming to a close.
"I think the emotion won't hit until it's actually over," Thorson said about Senior Day. "I think you just go out ready to play, to perform and do your best, and when the time runs out I think it will hit me. I think it will hit all of the seniors, and I don't know what that moment's going to be like. I guess I'll just have to wait and see, but up until that point, the attention's just going to be focused on performing and doing my assignment and just kind of treating it like all the other games."
Mendenhall said he isn't worried about the emotions of Senior Day being a distraction when the team goes up against the Aggies. Some of the non-seniors, however, may view it as a source of motivation as they seek to send out their teammates on a high note.
Junior Eathyn Manumaleuna said "we're trying to make it as memorable as we can [and] to be more dominant, as we were [against Idaho]. We just try to play for them since it's their last home game."
Thorson said he thinks the biggest contribution of this senior class has been leadership.
"This preseason there was a lot of hype about going independent, and a lot of different thoughts [and] things that were going on. I think the seniors did a good job of doing player-run practices all summer, just kind of leading the way of the attitudes and what the younger players were going to think about it."
Some of this senior class's contributions include Jordan Pendleton making plays all over the field against Oklahoma and tormenting Utah quarterback Jordan Wynn in 2009; McKay Jacobson's game-winning touchdown against Oklahoma, the long reception on the game-winning drive against Utah State this year, and the big reception to set up the game-winning John Beck-to-Jonny Harline touchdown against Utah in 2006; Bryan Kariya making plays while filling in for an injured Harvey Unga against Oklahoma; Matt Reynolds playing most of the 2009 Utah game on a sprained ankle; and J.J. Di Luigi carrying the offense during part of the 2010 season while the team was struggling.
Other seniors, meanwhile, may not have been as well-known, but they contributed in their own ways. That includes providing depth, playing "unglamorous" positions, and contributing to the scout team.
As for what he will remember about this senior class, Mendenhall said, "Resiliency and success. They've won a lot of games and they've helped our program do a lot of different things. Over their span here, it'd be fun to mark how many games they've won in terms of against other BYU teams in different eras. But they've really helped us, and in a pretty unique approach in terms of program philosophy, and they've endured the whole thing and embraced it. And so I kind of view them not necessarily as the initial pioneer group that came in, but they were the ones that kind of just continued it and carried it on at even a higher level I think."