This story was excerpted from Steve Gilbert's D-backs newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

The first two days of the trip were a challenge for the D-backs off the field in St. Louis. COVID-19 issues caused a pair of players to wind up on the injured list, one just before the series opener against the Cardinals and another the next day.

Fans will read about the transaction and see a new player in uniform, but how these things happen is far more complicated than you might think.

It starts before every game when manager Torey Lovullo will sit down with whichever member of the baseball operations staff is on the trip. In St. Louis that was assistant GM Jason McLeod.

They will talk about how the pitching situation looks. Is the bullpen on fumes? What if they get a short start that night from a starting pitcher? Will they need to add an arm from the Minor Leagues? They will again meet after the game to discuss where things stand.

There are a number of people that are involved in deciding who it is that will come up, including farm director Josh Barfield. Once it's determined who the player will be, Barfield puts the wheels in motion.

That involves notifying senior director of team travel Roger Riley, who travels with the Major League club, so he can arrange flights for the players coming (and going).

"Roger works magic," Barfield said. "He can usually find and book a flight for them within five minutes or so."

That, of course, is more difficult these days with so many flights being cancelled or delayed as well as full flights, but Riley, who has worked for the D-backs since 1998 and before that was in a similar role with the Padres, is one of the best in the business at getting it done.

There's not a lot of time either. For example, in the case of last weekend, the Triple-A Reno players heading to meet the team in St. Louis were in El Paso for a series and they were told they were being promoted just an hour and a half before their flight was scheduled to leave.

That's only one part of the equation, though. Sometimes calling a guy up from Reno leaves the Aces shorthanded and Barfield has to find a way to fill that hole by moving another player up from Double-A Amarillo or somewhere else in the system.

"There's a trickle-down effect, but I think that's the fun part of the job," Barfield said. "It's like trying to make the puzzle fit together. We have a lot of capable guys that when they're given their opportunity they step up."

Reno has 33 players on its roster, so that provides a little bit of a cushion, but not as much as in the past when teams were allowed to have as many players in their organization as they wanted. The D-backs carried over 200 at that point, but now are limited to 180 by MLB rules.

Lovullo marvels at the way it's all handled by his front office.

"There's a string of names in a text [thread] and it describes what's going to happen in very great detail," Lovullo explained. "What's happening today, what's happening tomorrow and what it looks like if A happens or B happens. Josh is fantastic at getting the information and getting the player ready. A lot of people don't understand it. It's like the player just magically appears. They don't understand how hard it is to make it all work."