ALLEN PARK, Mich. -- There wasn't one specific thing that happened, one obvious moment like when previous Detroit Lions coaches were fired.

There was no epic collapse or sideline outburst. With Jim Caldwell, a bunch of things just piled up. It was those things, those mistakes, that led to his dismissal Monday as Lions coach after four seasons and more wins than losses.

Caldwell's job is no longer his because his teams had the same issues pop up over and over again. The slow starts that were often forgotten because of Matthew Stafford's late-game comebacks in 2016 turned into a much larger problem in 2017 when Stafford couldn’t finish off those rallies.

Too often on critical downs, the Lions played with fewer than 11 men on the field without noticing it or calling a timeout -- a major coaching gaffe.

Caldwell's most glaring on-field mistake was the defense of the Hail Mary by Green Bay's Aaron Rodgers to Richard Rodgers on an untimed down in 2015. It gave the Packers a win in a nationally televised game and killed all the momentum Detroit had built with three straight wins after a 1-7 start that led to the firings of the Lions' team president, general manager, offensive coordinator and offensive line coaches at various parts of that season. Caldwell said after that game that the Lions were preparing to defend "more of that pass-back-and-forth kind of thing" instead of a throw even though Aaron Rodgers has one of the strongest arms in the game.

Caldwell's teams seemed unprepared for big games, with a 4-23 record against teams that finished the season with winning records. He was 0-2 in playoff games. He was 0-4 in games when a win would have either locked up or brought Detroit extremely close to its divisional title for the first time since 1993 -- losing at Green Bay in Week 17 in 2014 and then the final three games of the 2016 season, including in Week 17 to the Packers.

The Lions lost three of those regular-season games -- and last season's playoff game in Seattle -- by double digits.

Caldwell defended that -- or tried to -- last week, saying he looked at it differently, and sometimes a game in Week 2 was a big game for making the playoffs.

"Yeah, I'd look at it, but there's also a number of them that we've won to get us in position to where we made it into the playoffs," Caldwell said. "And so no matter when that comes, that could be the second game of the season, that adds up. So, and we look at that more so than we look at anything else.

"You can define it the way you want to or look at it the way you want to in that regard. But we let an opportunity slip by us the other day, and we just got to keep getting better."

The opportunity the Lions let slip this season came multiple times. By Caldwell's definition, games against Atlanta and Carolina at home were big games the Lions could have -- and potentially should have -- won. Those losses put Detroit in a tough tiebreaker situation, and had the Lions won their bigger games later in the season, it might have been enough to get him a fifth season in Detroit.

But the Lions lost on Thanksgiving to Minnesota, all but wrapping up the NFC North for the Vikings in November during a season when Aaron Rodgers was an injured nonfactor. The next week, they were blown out by Baltimore, putting them in a must-win-plus-needing-help position the rest of the season.

But the opportunity Caldwell was mentioning, a 26-17 loss to Cincinnati against a team out of the playoff picture, was so unlike games under Caldwell. Typically Caldwell's teams have beaten bad teams. They looked wholly unprepared and lifeless against the Bengals in a must-win game -- and if GM Bob Quinn had any thoughts of keeping Caldwell before that loss, they likely disappeared after it.

This isn't to say Caldwell was a disaster for the Lions. He turned around the team culture in the locker room and, for the most part, made the Lions a more disciplined team. He finished with a 36-28 record, best among Detroit coaches during the Super Bowl era. He also helped turn Stafford into a top-10 quarterback, and his staff should get credit for Darius Slay's ascension to one of the best cornerbacks in the league.

Caldwell earned the respect of his players for the way he handled them during the week and treated them off the field. Those same players have fought for him to remain Detroit's coach many, many times over the past three seasons. At one point, it seemed like every time Caldwell's job was in trouble, the Lions played their best.

That didn’t happen this season. It is part of the reason Caldwell's tenure is ending after four seasons despite three winning records.

It was the on-field results when games mattered, not the record, that did Caldwell in.

Caldwell was asked last week why he believed he should be the Lions' coach in 2018. As he always does, he said it wasn't up to him. But then he explained, in some ways, his philosophy of coaching and dealing with people.

"The fact of the matter is that's not for me to judge," Caldwell said. "I do my job. I work at it. I work at it hard. I deal with my people fairly. We try to win as many games as we possibly can. That decision is up to someone else, not me."

Caldwell has done all of those things. His players -- and others around the building -- all genuinely like the man. He raised expectations for the Lions to where just being in contention for the playoffs every year, which is where the Lions are now, is no longer good enough.

Detroit made the playoffs last season in part because Washington lost in Week 17, but the Lions struggled in games that mattered in 2017. Struggled in games that, had they won, would have met those expectations the franchise now has.

Those types of losses piled up -- and that was enough for Detroit to go searching for its seventh head coach since the turn of the century.