BOSTON — A week ago Chance Adams was just slightly more possible to start Saturday for the Yankees on national TV against the Red Sox as Ron Guidry.

Brian Cashman used the word “cascade” and “dominoes” — as in falling dominoes — to explain the machinations that led to Adams being slated to make his major league debut against the highest-scoring team in the majors.

Welcome, to 10 steps to a Chance Adams start:

1. It begins with – irony alert — the Yankees getting more starters. The Yanks saw that as their priority at the trade deadline to get at least one starter. They got two in J.A. Happ and Lance Lynn.

2. That means two roster spots are needed, three with Zach Britton added as well. You have those three plus Luis Severino, Masahiro Tanaka, CC Sabathia, Sonny Gray, Aroldis Chapman, Dellin Betances, David Robertson, Chad Green and Jonathan Holder as the must haves on the staff. That is 12. The Yankees were willing to keep going with 13 for depth in that area, although it would mean continuing to play with a short bench.

3. That meant the Yankees could pick one from A.J. Cole, Chasen Shreve and Adam Warren. The complication – all three were out of options. Thus, they could not be sent to the minors. One other complication, Warren was probably the most stretched out of all the relievers, possibly having 45 pitches to give if necessary. The Yanks worried that left them without a true long man.

4. That is why when Lynn became available the Yankees decided to pounce. They saw him as rotation protection, but also a guy stretched out to 80-100 pitches who they knew from research could warm up quickly and, thus, re-adjust to the pen and a long relief role.

The Yankees had a deal worked out with the Twins for Lynn, but Cashman only was doing it if the Mariners agreed to a proposal for Warren for $1.25 million in international slot money. Seattle ultimately agreed.

5. Yes, we should probably discuss the slot money. Looking at not having a high first-round pick for a while — and perhaps a second-round pick next June if they sign a likely qualified free agent such as Patrick Corbin — the Yanks wanted to accumulate the maximum allowed in international slot money ($3.75 million) to try to land top amateurs in that forum. They did that with the Warren deal and also sending Shreve and Giovanny Gallegos to the Cardinals for slot money and Luke Voit and Caleb Frare to the White Sox for slot dough. Internally, the Yanks decided Cole was pitching the best and had control beyond this year and he won the out-of-option battle against Shreve and Warren (a free agent after this season).

6. Happ scheduled to start Saturday came down with hand, foot and mouth disease and, after initial optimism that he could recover in time to start, needed to be put on the DL.

7. Lynn, the next choice to start, was needed for 4 1/3 innings and 71 pitches of long relief when Sonny Gray was bombed against the Orioles on Wednesday to get bounced from the rotation. So that meant Lynn could not start Saturday.

8. Luis Cessa was the next choice for Saturday, but he also was long relief protection Friday. Aaron Boone desperately did not want to use Cessa on Thursday night, but Sabathia was in trouble in all three of his innings and taxed with 77 pitches. Then Jonathan Holder faced seven batters and did not retire any, Boone letting him go extra batters because he did not want to spin the wheel that would lead to Cessa. Then Chad Green was also bad in the fourth inning.

At that point, Boone decided to sacrifice Cessa to protect his better relievers for the rest of the series.

9. This is probably the moment to mention that injuries to Domingo German and Jonathan Loaisiga factor in as well. They would be options to start or provide long relief, but without them around, the Yankees lack 40-man roster options to give them length as a starter or reliever.

10. Which brings us back to Adams. Part of the reason that the Yanks traded many of the youngsters they did was to make it easier to put Adams on the 40-man roster in the offseason when he must be placed or be vulnerable in the Rule 5 draft.

The Yanks also believed that Adams and top pitching prospect, Justus Sheffield, could be put on the 40-man in September to provide relief. But the clock is being sped up due to the cascade, because of the falling dominoes. That also included Sheffield starting at Triple-A on Thursday and not being available to go Saturday.

Suddenly trades, injuries, short starts and use of others led to essentially one choice that even a week earlier seemed dubious:

Chance Adams starting Saturday at Fenway.