Darnay Holmes stood in front of a crowd of inquisitive football minds and warned that competing against anyone other than yesterday’s version of yourself is a “waste of energy.”

Holmes was addressing high school players who attended the Sports International camp at Drew University last week, but he could’ve been advising his fellow Giants defensive backs.

Or speaking into a mirror about his own upcoming training-camp battle against Cor’Dale Flott and other dark-horse candidates to be the starting slot cornerback.

“It’s a battle each year for me,” Holmes later told The Post. “It’s always an opportunity to present myself to be one of the 32 best nickels [in the NFL]. I’m never a guy who shies away from competition, so I’m excited. We’re ready to get each other better and do what’s best for the team.”

Holmes, 25, made one of the biggest plays of last season — forcing an end-zone incompletion to seal a Week 15 win against Washington — but Flott was drafted by the current regime to play in the slot.

He was forced to the perimeter as a rookie by teammates’ injuries and performed better than he had in the slot, but long-term plans remain unchanged as Flott and Holmes rotated with the starting secondary — ahead of third-teamer Zyon Gilbert — during OTAs and minicamp.

“It’s an open competition, but I’ll just let that be when I get on the field,” Flott told The Post at the same camp. “I got a little taste of everything. The transition helped me be able to attack the nickel but not be too surprised if I have to move out there again.”

Flott, 21, spent his first NFL offseason training around the country with fellow former LSU stars Derek Stingley Jr., Kelvin Joseph and Patrick Queen.

He is noticeably bulked up — which could help him stay on the field when the defense calls for a bigger slot to stop the run — to attack one specific skill.

“Mostly my tackling — and that just comes with body composition and gaining a little extra,” Flott said of his offseason focus. “With my quickness and my length, there aren’t too many 6-foot-2 people that move like a shifty guy, so I take pride in that and I’m ready to play it.”

Holmes’ first step to adding to his 11 career starts is showing desired improvements since last season, his third.

That starts with less reliance on his hands after he was flagged for six holding and two pass interference penalties — and got away with early contact on that season-turning pass break-up — last season.

“They judge me based off the tape I put out there, and I feel like I did the things to get better during the offseason — and I’m not done just yet,” Holmes said. “I feel like the things that have hindered my play are actually going to be a tool that allows me to be my best self.

“I want to be penalty-free — not as handsy. People don’t understand nickel is a profound position and you can’t really focus on what the critics are saying. There are things my coach wanted me to work on, things I knew I needed to work on, and once I heard from their mouth that it was something I was already crafting on, I had peace with the situation.”

The Giants beefed up their No. 28-ranked run defense with the front-seven signings of A’Shawn Robinson, Rakeem Nunez-Roches and Bobby Okereke, but at what cost?

Even if first-round rookie Deonte Banks seamlessly replaces free-agent cornerback Fabian Moreau, one safety job — vacated by Julian Love — is also up for grabs.

“I’m excited for what the future holds for all of us,” said Holmes, crediting defensive backs coach Jerome Henderson and veteran Adoree’ Jackson as tone-setters. “We have a room that is not selfish and wants to be the best. When you have that, there’s no ceiling.”

Holmes stressed to campers the importance of considering consequences in decision-making, and Flott urged his audience to “believe in yourself” while discovering your strengths and weaknesses on the job.

Sounds like words of wisdom for the young Giants secondary to borrow.