– There are 183 days in a major league baseball season. Once a player reaches 172 days, he is credited with a full season of service time. That is also the maximum number of days — 172 — that a player can compile in a season.

A player needs six full seasons to become a free agent. For instance:

Reliever Kevin Jepsen had five years, 163 days of service time at the end of last season, meaning the Twins still controlled his contract rights. Third baseman Trevor Plouffe will have five years, 162 days of service time at the end of this season, meaning he could not hit the free-agent market until after the 2017 season.

The 12-day difference between an actual season and the requirement for a year of service time will be a point of contention as the Major League Baseball Players Association and the Commissioner’s Office negotiate the labor contract that expires at the end of this season.

It became a much-publicized issue last spring, when slugging prospect Kris Bryant tore up the Cactus League for the Chicago Cubs, then was sent to the minor leagues for just long enough to avoid being with the Cubs for 172 days.

Bryant’s agent, Scott Boras, screamed about this to the point that Commissioner Rob Manfred told him to butt out … that it was none of his business as to how the Cubs decided to handle Bryant.

The Cubs’ strategy of trying to guarantee themselves a seventh year of Bryant — the 171 days of 2015, plus six full seasons to follow — caused followers of the Twins to speculate that the team would follow a similar strategy with pitcher Jose Berrios.

This speculation was coming from people who turned on the Twins during the four woeful seasons from the 2011 to 2014 and reached the conclusion that all of the team’s personnel decisions were intended to keep the payroll under tight control.

It also wildly overstated Berrios’ standing as a prospect — a 21-year-old pitcher with a chance to develop into an ace, compared to Bryant, a player who clearly was ready to be a hitting star.

Much Hades had been raised by Twins followers in mid-August of last season. Starting pitcher Phil Hughes was put on the disabled list, and the Twins recalled Tyler Duffey to replace him in the rotation.

Duffey had made his first big-league start in Toronto two weeks earlier and lasted for two dreadful innings.

And now the Twins were bringing him back. We screamed. We stomped our feet. We demanded Berrios.

And then Duffey stuck around for 10 starts and was the most consistent starter in the Twins’ feisty, failed attempt to gain the American League’s second wild card.

The fact Duffey would be returning with three other righthanded starters in Hughes, Ervin Santana and Kyle Gibson (as well as the lefthanded Tommy Milone) did not prevent the story line from developing over the winter:

If the Twins did not put Berrios in the rotation immediately to start the 2016 season, it would be another example that the owners, “The Pohlads,” were only concerned about money.

Berrios was sent to the minors March 18. It wasn’t to avoid having him become a free agent after the 2022 season, rather than 2021. It was because the young man was only moderately impressive this spring.

There was nothing Bryant-like hollering out that Berrios absolutely deserved to be in the Twins rotation to open the 2016 season.

We now have moved to another crisis for the Pohlads-are-cheap crowd:

The status of Duffey, the 25-year-old with that solid 10-start run on his résumé.

Manager Paul Molitor and pitching coach Neil Allen arrived in Florida with a full belief that Duffey would be in the rotation. All they had to see was a reasonable facsimile of the pitcher they saw for six weeks last season.

Santana, Gibson and Hughes were locks. Duffey was the fourth starter. The fifth would be Milone or Ricky Nolasco — or perhaps Berrios, if he was lights out (which he wasn’t).

That was Plan A.

The trouble is, 10 starts from a pitcher who wasn’t on the Twins’ top 20 prospects list a year ago … that doesn’t make you a sure thing.

Duffey had to provide that facsimile of 2015 to guarantee his spot in the rotation. So far, he hasn’t.

The outs being recorded by Milone and the curveball being thrown by Nolasco in recent outings have been more impressive than what’s been offered by Duffey.

That rotation spot still would be there for Duffey, if he has a strong effort Monday against Pittsburgh.

Another clunker — teamed with more sharpness from Milone and Nolasco — and Duffey figures to start the season with Berrios in the rotation at Class AAA Rochester.

Some decisions can be best made on performance in spring training, and Duffey (so far) and Berrios have done that for the Twins.