DETROIT -- There’s 11:30 left in the fourth quarter of the Detroit Lions’ third preseason game, with the Lions facing the Buffalo Bills, and general manager Bob Quinn is staring down toward the field from his seventh-level box inside Ford Field. Below, the team he’s been building over the past three and a half years is preparing to receive a punt.

He’s watching two players in particular on this play, nearside jammer -- or “vice,” as Quinn calls him -- Johnathan Alston and returner Tom Kennedy. For most plays in a game, other than big plays and third-down situations, Quinn will pick one or two players or a position group to focus on.

“You can’t watch 11 guys,” Quinn said.

Not when you focus on evaluations, at least. Here, he’s studying the combination between jammer and returner. Before the ball is off Buffalo punter Corey Bojorquez’s foot, Bills gunner Robert Foster cuts inside of Alston and sprints toward Kennedy.

“That was not good,” Quinn said -- a quick evaluation of Alston’s inability to block Foster.

Kennedy fair catches the ball at the 5-yard line, a decision Quinn initially deems as “maybe OK judgment,” in part because he only saw part of what Kennedy was likely seeing on the field.

Quinn makes it clear one play does not make or break a player’s chances to make the roster. Every player has good plays and bad. Consistency, he says, is the key. It comes down to the cumulative evaluation of spring and summer as he tries to find the 53 players, plus 10 practice-squad guys, he feels will make up the best possible initial roster for 2019.

As part of that process, Quinn let ESPN inside the general manager’s suite to offer a look at player evaluations and what a general manager does during a game. The stipulations were simple: No recorder could be used and whatever was said was fair game unless otherwise specified.

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During the game Friday night, Quinn and his staff are trying to get a feel for how players are performing. Saturday morning, at 6 a.m., Quinn will begin a three-and-a-half-hour film session, breaking down the game in its entirety.

“Everything (at the game) is preliminary,” Quinn said. “I don’t want to get too high or too low before I go through the film.”

In the preseason, in-game evaluations are harder. Because there isn’t as much scheming involved and there are 90 players on the roster with guys shuffling in and out, he’s not as familiar with player assignments as he would be during the regular season with 46 active players.

He will confirm or revise his in-game evaluation Saturday morning. For example, regarding Kennedy’s punt return, Quinn will later modify his initial opinion, calling it a poor decision. Kennedy should have taken the chance it bounces into the end zone versus a Bills player downing it inside the 5-yard line.

Again, Quinn stresses it’s only one play.

It’s quiet in here, almost eerily so. The lack of sound is surprising. It’s an open-air box but it feels more like you’re in an office building than a stadium with thousands of people, even during a preseason game.

Quinn says this is typical.

“It’s an interesting dichotomy,” Quinn said. “When I’m in the press box, you can’t cheer or show emotion. It’s hard.” He’s referring to the setup in Chicago and sometimes Green Bay, where he sits right behind or close to media members. “Here,” he continued, “I can do whatever I want.” Still, though, it’s mostly silent.

Five men are in the small, two-tiered box. They are Quinn and his brain trust: Kyle O’Brien, vice president of player personnel, who sits directly to his left in the front row. In the corner is Mike Disner, vice president of football administration, who was hired this offseason. In the elevated second row are Lance Newmark, director of player personnel, and Rob Lohman, director of pro scouting. Before every game, they discuss who is watching what, including five to seven players O’Brien, Newmark and Lohman will focus on to create evaluations.

From his box at Ford Field, Bob Quinn tries to watch individual players and not all 11 players at once. Michael Rothstein/ESPN

By noon or 1 p.m. the next day, O’Brien, Newmark and Lohman file reports. This gives them time to rewatch the game and provide detailed player evaluations along with other notes they spot about the team. Disner’s role is different. He is more concerned with operations on the field and making sure everyone on the sideline is in compliance with NFL rules.

During games, conversation is minimal. Usually it will come if an injury occurs and they need to make in-game calls to the agents of potential replacements to schedule Monday or Tuesday visits. Two years ago, when punter Kasey Redfern was injured in the first quarter of the season opener against Arizona, Quinn had then-director of pro scouting Brendan Prophett on the phone with agents. By Sunday night, the Lions had punters flying to Detroit for workouts. Now, both Disner and Lohman handle those duties.

Injuries, Quinn said, are “the worst part about the game.” Waiting on the information after a player is hurt, like starters Frank Ragnow and Jarrad Davis were earlier Friday evening, is the most difficult.

“You’re concerned,” Quinn said. “And you wait and wait and get a call on it 15 minutes later. Hopefully you’re relieved and it isn’t too serious.”

That’s when he’ll usually receive an initial prognosis -- on Friday night, however, he doesn’t relay any information on Ragnow or Davis. Neither injury looked particularly good live. The next day, Lions coach Matt Patricia said neither injury would be season-ending.

For Quinn, evaluating comes down to more than what happens on the field during games and practices. He eyes everything. Sometimes he keeps notes to discuss later with Patricia, who is usually up against the sideline and unable to see everything. Even from Patricia’s elevated perch behind the bench as he recovers from an Achilles injury, he’s still focused on in-game adjustments and playcalls.

From the box, Quinn sometimes peeks at Detroit’s sidelines. Sometimes he’s paying attention to substitution speed and the apparent level of communication so he can report back to Patricia later.

But often, he’s watching players to see if they are engaged in the action or the coaching on the sidelines. What is the energy like? It’s harder during the preseason, when guys sometimes either aren’t playing or are pulled early.

As he’s saying this, Al Golden meets with his linebackers. Quinn notes the seated linebackers -- when players are sitting, it usually means they are the ones in the game: Miles Killebrew, Anthony Pittman, Malik Carney and Garret Dooley. Quinn sees Jalen Reeves-Maybin, Jahlani Tavai and Christian Jones -- players pulled over an hour ago -- listening next to Golden.

Off to the side, safety Quandre Diggs is staring at a tablet. These are details Quinn can’t pick up on tape the next day, so it’s important to watch for them in real time. He doesn’t spend all his time watching the sidelines. In the regular season, it’s rarely an issue, but in the preseason he’s curious.

“[With] 11:24 to go in the fourth quarter, and they are into it,” Quinn said. “Yeah. Everything matters.”

Mark Thompson is running. Hard. The Lions hand the running back the ball five times in the fourth quarter. After almost every carry, either Quinn or O’Brien gives a short, staccato, “Good run, good run,” even while sometimes mid-sentence talking about something else.

Thompson, on the surface, appears to be a longshot to make the roster. Detroit has its top back, Kerryon Johnson. The club signed C.J. Anderson in the offseason and drafted Ty Johnson in the sixth round. Days after this game, the Lions cut Zach Zenner, a move that seems likely to keep the team light at running back.

Thompson’s performance is a sign of improvement. When he scores a 1-yard touchdown in the fourth quarter, both O’Brien and Lohman are happy.

“He’s a big guy, physical guy. Downhill running,” Quinn said. “Where we’ve been getting on him is pad level. Big and physical, but upright.”

Quinn can’t say in the moment how much better his pad level was, but it’s on his mind to make sure he pays attention to it. Later, he determines that he saw some good, some bad.

Quinn’s note-taking process is not much different from that of a reporter. To his immediate left are small, black binoculars he’ll use -- particularly in the preseason -- to keep track of players on the field and to watch certain actions. Next to the binoculars, in a black, leather case, is his small tablet with a separate keyboard underneath. He has NFL GSIS, a stat-tracking website, up on one tab. He uses it to track the Lions-Bills game. In the regular season, it allows him to keep up with other teams as well.

An Excel spreadsheet sits open on his screen. He has different headings for offense, defense and special teams, and boxes numbered on the side with “1, 2, 3,” to correspond to the drives. On the first offensive series Friday night, he notes “33c, 11c.” That corresponds to catches by Kerryon Johnson and Marvin Jones. He also has a separate part of the sheet for injury notations.

Below that is a general notes section -- he marks questions about officiating or specific things to watch for the next day.

“Look back, where are our series,” Quinn said. “I just try to keep track of something.”

Even though it’s the preseason and there’s a balance between player development, the competitive fire is still hot. With 4:50 left, the Lions get the ball back after a 17-yard Kennedy punt return -- “He got the yards that were there,” Quinn said. The play was not blocked particularly well, according to both his in-game and final evaluations.

The focus, in this moment, is clear.

“We want to win this game,” Quinn said, the most animated he’s been the entire quarter. “It’s the preseason, but we want to get in the habit of winning.”

With around four minutes remaining, Josh Johnson scrambles for 11 yards. Quinn is cheering on the quarterback he signed two weeks ago, like he does all 90 players on his roster: “Go Josh.” It sets up a fourth-and-4. In the booth, talking to himself, Quinn wants to “Go for it.” Patricia does -- and gets the conversion -- with 3:47 left. Detroit is moving down the field, coming closer to Quinn’s wish of a Lions win.

Then Johnson completes a slant route to rookie receiver Travis Fulgham, who is in competition for a depth receiver spot. Fulgham has the ball ripped from his hands. Quinn curses. The Bills recover.

Quinn refocuses. He grabs his binoculars and looks at the sideline. He wants to see how Fulgham handles the moment. Quinn seems impressed by the receiver’s demeanor. “Looked like he didn’t lose his cool,” Quinn said. Fulgham, taken in the sixth round this year, will later act similarly, saying he knows he needs to learn from it.

How much does a play like that weigh for someone in a tight competition and potentially on the bubble? It depends. As Quinn said earlier, it’s only one play.

“The games weigh a little more,” Quinn said. “But we’ve had like 20 practices. It’s all part of the evaluation.”

On Saturday morning, with his in-game observations available, this session is where he’ll put his “hardcore notes” down in the massive Microsoft Word document he keeps on every player. The document goes back to the spring, a running file he scours to see if his thoughts have changed or if there has been improvement. His evaluation can be different from that of the coaches. Assistants have to be more in the process of the next day and next game. Patricia and Quinn think long-term as well as short-term on roster decisions.

“The coaches are in the moment,” Quinn said. “I look at a holistic view of the whole body of work.”

It’s a body of work that, by Friday night, was nearing completion. He shuts his tablet and puts his binoculars back in a small, black case with 1:47 left and the Bills kneeling out the clock.

As he walks out of the box, he knows in a week he’ll start finalizing decisions that will change lives and shape how the Lions fare in 2019 -- one of the most crucial, and difficult, parts of his job.