Those in the business of winning and achieving, particularly in sports, often say that having success is not the hart part.

Sustaining success after having success is the hard part.

The stakes get higher. The pressure becomes more palpable. Your positive accomplishments are no longer surprises but rather expectations. Negative turns become magnified.

That idea seems to define the Mike Zimmer coaching era with the Vikings — a time that came to an end Monday with a firing that was foreshadowed four years ago.

Zimmer, a coach who could be extremely candid, was perhaps at the peak of that openness at the NFL Scouting Combine in 2018 as he talked about the Vikings' looming decision on quarterbacks.

"You just have to pick out the right one [quarterback] that's going to help your football team the best," Zimmer said. "And where you can still do things at other positions. You don't want to go crazy here."

The undercurrent of that comment and a bolder one I will get to in a moment, paraphrasing Zimmer: We just won 13 games and went to the NFC title game with Case Keenum. Two years before that we won 11 games and should have won at least one playoff game with Teddy Bridgewater. Let's spend wisely on a QB and keep building around defense.

A couple weeks later, the Vikings signed Kirk Cousins to a three-year, $84 million fully guaranteed contract.

And now we have an even split: The Zimmer era divided neatly into two halves. Four years before Cousins signed and four years after Cousins. Four years where the Vikings were building a winner. Four years where they were expected to win.

Zimmer's teams went 40-27 in those first four years (including 1-2 in the postseason in two playoff appearances). Zimmer's teams went 34-32-1 in those final four with Cousins (including 1-1 in one playoff appearance.

Some of it is merely correlation. Some is causation. Some of it has little to do with Zimmer. Some of it was self-fulfilling prophecy. All of it was fodder for Monday's Daily Delivery podcast with Patrick Reusse.

Signing Cousins raised the stakes for the Vikings. It was an all-in move, but the cost of his contract meant sacrificing some roster depth in other areas.

The increased pressure also seemed to influence Zimmer's decisions and demeanor — most notably when rookie kicker Daniel Carlson was cut after one disastrous game in Week 2 against Green Bay in 2018. Carlson has gone on to become one of the NFL's best kickers with the Raiders.

Zimmer fired John DeFilippo later that season, part of a revolving door of offensive coordinators that will undoubtedly see the Vikings hire their seventh in seven seasons in 2022. (In fairness, two of those coordinators left for head coaching jobs).

Cousins and Zimmer never seemed to mesh, with Everson Griffen famously tweeting nearly a year ago that the coach never wanted the QB. The weekly meetings between the QB and coach this season seemed to strengthen whatever uneasy truce existed between them, but the tension was still noticeable at times.

It's too easy to draw a straight line from Cousins signing to Zimmer's firing, but those four-year splits sure do offer a clean line. There was before Cousins. There was after Cousins.

And in-between, there was this prescient Zimmer quote about the QB search from that 2018 combine session:

"It's important for myself and Rick and the organization to pick the right guy that is going to help us continue to move forward," Zimmer said. "If we don't do that, then I'll probably be fired."

As it turns out, Spielman was as well.