The internet is abuzz with every casting announcement for the Marvel Cinematic Universe, speculating about the narrative, but the reality behind the selection process for the next big movie might be less thrilling.

In a conversation with the Hollywood Reporter, the Russo Brothers (Electric State) discussed revisiting the drawing board with Marvel to work on the upcoming Avengers films, Avengers: Doomsday and Avengers: Secret Wars, which will feature Robert Downey Jr., formerly Iron Man, playing the role of Doctor Doom.

This isn’t the first time they’ve taken a risk with the franchise’s leading star. Joe Russo recalled approaching Downey, then the face of the MCU as Iron Man, to play the villain in Captain America: Civil War — a movie not even titled after his character. The pitch was a success, with Downey agreeing to take on the role, which ultimately led to the massive success of Infinity War and Endgame.

In the past, the Russos used a set of baseball-style cards featuring their superhero cast to keep track of the number of films they were contracted for. When asked by THR if they still use this method, Anthony Russo replied, “Yes, we continue to use the baseball cards.” This approach helps shape the Marvel film they’re working on.

Joe added, “Now they have magnets on them, so we can put them on a board and look at them. It’s the only way to keep track of the large number of characters we’re working with.”

It’s starting to sound more like a budgeting process than storytelling, but Anthony downplayed this aspect. “As for how we decide who’s in the movies, it’s a long creative process of exploring where we want to take the story. What’s the most surprising and exciting area for us to explore, and which characters help us achieve that?”

However, the stars’ contracts and financial statistics clearly play a role; if they didn’t, there would be no need for the baseball cards. With the next massive Marvel movie crossover on the horizon, more cards have been added to the deck, including The Fantastic Four: First Steps, set to release this summer. The question remains whether the Russos will have more star players on board or if audiences have moved on from overcrowded character lineups overpowering the movie’s story. Replicating this approach on a larger scale is a gamble, but we’ll see if it pays off with the release of Avengers: Doomsday in 2026.

For more io9 news, check out the expected release dates for upcoming Marvel, Star Wars, and Star Trek releases, what’s next for the DC Universe on film and TV, and everything you need to know about the future of Doctor Who.