What happened: Jacob Misiorowski, Junior Caminero and Randy Arozarena join Harper and Freeman on the signed baseball, with fan entries open via repost and reply. The giveaway ties into the MLB and Marvel crossover preview for Avengers: Doomsday that aired during the World Series.

Why it matters: Pairing veteran stars with young talent like Caminero and Misiorowski extends the league's postseason entertainment tie-in across digital fan channels during the championship series.

What to watch: MLB will select the prize winner from eligible postseason sweepstakes entries.