Robert Saleh likes to refer to Football 101, 301 and 501, those imaginary "college" courses that get tougher as the numbers and years of experience go higher. This week the Jets head coach read from the syllabus on his course that could be titled: "The Mathematical Underpinnings of Optimal Defensive Line Reps in the NFL."

It started a few days earlier when coordinator Jeff Ulbrich stated that 30 to 35 snaps a game is the range he seeks for his D-linemen.

"Whether they're run-stopping or jumping out of their shoes and pass-rushing, there's a level of fatigue that's associated with how we play," Ulbrich said. "We don't catch blocks, we don't read blocks — things are on our terms. When you play like that, with your hair on fire, with the energy and the strain that we demand of them, asking them to play any more than 35 snaps, I think, is detrimental to their health and the quality of play."

Saleh expanded on that topic before Wednesday's OTA practice.

"We ask our D-line to do a lot from an attack standpoint, so physically it is hard, unless you're an absolute freakazoid like Aaron Donald, who can go forever," he said. "It's really not a 30-35 snap count, it's more of a percentage. There are obviously variables, but you're trying to hit a 70 percent mark. There are 60 to 65 snaps on average for a defensive team, so you're looking at 40 to 45 snaps. ... In a perfect scenario where we're winning games, 30 to 35 of those snaps are against the pass.

"Let's say we start the game, and I'll use Quinnen [Williams] as an example. He rolls out on first down, second down, they convert on third down. Well, get Quinnen off the field. Then he's not on the field for first down, second down. Third down, he's back on and we get off the field. In that scenario, he played four of six snaps, 67 percent."

The point of the math, both simple and advanced, Saleh explained, is to optimize the Jets linemen's input in the rotation that he, Ulbrich and DL coach Aaron Whitecotton began building last season.

"If you went on average, it's probably in that 70 percent range," the head coach said. "I think that's what we were hitting in San Francisco with DeForest Buckner, [Nick] Bosa, [Arik] Armstead. It's not a perfect science. If you're playing 90 snaps in a game, you're going to be in the 60-snap range.

"You're just trying to pace these guys so they're as fresh as possible when crunch time hits, those third downs, those two minutes when we need a play."

It's hard to compare the 4-3 Jets with their 17-game schedule to the 3-4 teams that played 16 games, but for what it's worth, six linemen last season racked up more than 400 snaps and eight had 300-plus, led by John Franklin-Myers' 716 snaps and 66% of the plays. The most in any of the Jets' previous nine seasons were four players with 400-plus plays and six with 300-plus.

The whole point of this discussion is that while the Jets began constructing that rotation last year, the D-line and the entire defense were far from perfect. But this year's depth chart will include many of the following: JFM, Williams, Sheldon Rankins, Nate Shepherd and Bryce Huff returning for another season in the system; Carl Lawson and Vinny Curry making their delayed Jets debuts; and free agents Solomon Thomas and Jacob Martin and draft choices Jermaine Johnson and Micheal Clemons arriving this offseason. The potential is there for a class of overachievers and several masters candidates.

"If you watch practice and OTAs, they work at an uncommon rate, and I think that's a testament to Aaron and the way he runs those guys and [assistant DL coach Greg] Scruggs," Ulbrich said. "It's also a testament to the makeup of that group, insanely obsessed from tip to tip, every single guy in that room.

"It's exciting to think about what they can become as a group."