How many spots will be open?
The National League will have 26 spots to fill, while the American League will have 25. The difference, of course, is that fans vote in a starting designated hitter for the AL team. There are 34 total roster spots for each league.
Who picks the reserves and pitchers?
In short, it's a group effort. The Player Ballot, the managers for each league (Terry Collins in the NL, and Ned Yost in the AL) and the fans all have a say in how the rosters round out.
How many Player Ballot selections are there?
Technically, it's more than just a "Player Ballot," because coaches and managers are also included in the process, but, anyway, the ballots gathered in all 30 clubhouses shortly before the roster announcements account for 16 players in the NL and 17 in the AL -- eight pitchers (five starters and three relievers), as well as one backup for each position (including DH in the AL).
What if the players select a guy already voted into the starting lineup by the fans?
Next man up. The guy who was second on the Player Ballot at that particular position is selected as the backup. This doesn't change the number of Player Ballot selections. The Player Ballot is basically used as a pecking order to fill the backup slot at each position.
How many manager selections are there?
The NL manager picks nine players: five pitchers and four position players. The AL manager makes seven selections: five pitchers and two positions players. The reason the AL manager has two fewer is because the fans pick the starting DH and the players pick the backup DH.
What about the fans?
They fill the 34th and final spot on each roster via the Final Vote ballot, which will feature five candidates from each league. Those five candidates are selected by the league's manager, with the assistance of the Commissioner's Office. It's a good chance to stymie a would-be snub situation.
Does every team have to be represented?
Yes, and it is the job of the manager for each league to ensure this stipulation is accounted for with their selections. It should be noted, however, that if a player is selected to the roster and can't participate for a particular reason, he does not necessarily have to replaced by a teammate.
How is the starting pitcher for each team determined?
By the league managers. The announcement is made the day before the game.
Who picks the replacements for injured players or those who decline to participate?
If an elected starter is going to be unable to play, the reserve who received the most votes on the Player Ballot at that particular position moves into the starting lineup. The roster replacement is then chosen by the league manager.
If a reserve or pitcher is going to be unable to play, the league manager and the Commissioner's Office work together to decide the replacement.
What if a pitcher isn't available because of his throwing schedule?
If a pitcher starts for his team on the final day before the All-Star break (in this case, on Sunday, July 10), he can be replaced on the league roster. Whereas the rule instituted in 2010 ruled such pitchers ineligible for the Midsummer Classic, the rule was altered in 2013 to give those pitchers the option of deciding if they want to pitch in the game -- but for a maximum of one inning or for a preset pitch count.
As with injured players, those affected by this rule are still considered to be All-Stars, and they are invited to make the trip to the game and be introduced beforehand. The replacement process is the same as it is for injured players.
So how many total All-Stars are we talking about here?
It depends on the year and the number of replacements necessary, but in the five-year period from 2011-15, the average was 79 All-Stars in all.
What if a selected player gets traded to a team in the opposite league before the All-Star Game?
This happened to Jeff Samardzija in 2014, when the Cubs dealt him to the A's. In such a scenario, the player is deemed ineligible to participate in the game but is still recognized as an All-Star for the original league. In Samardzija's case, he wore a generic NL jersey and All-Star Game cap for the pregame player introductions.