MLB regular-season extra innings can begin with a runner already on second base. That runner has not reached second through an unseen hit or a missing part of the broadcast. The rule changes the starting situation of the extra half-inning. It also needs to be kept separate from postseason baseball, where the automatic-runner arrangement does not apply.
Confirm the game and inning first
Look at whether the contest is a regular-season MLB game and whether regulation innings have ended. Do not apply the rule to every baseball competition or every tied score. Youth, international and postseason games can use different procedures. The inning display and the official event label provide the first clues. When a runner appears at second before the first extra-inning pitch, check that context before treating it as a faulty scoreboard or a stream that has skipped a plate appearance.
Read the new tactical starting point
A runner in scoring position changes the immediate choices for both sides. The batting team may consider ways to move that runner or bring them home, while the defense has to weigh the run risk against the value of an out. A safe-looking play can carry a different consequence with a runner already near home. This does not mean one particular tactic is always correct. Score, batting order, remaining personnel and what happened in the other half-inning still shape the decision.
Keep the two halves connected
The visiting team bats first in an extra inning, and the home team then has its own opportunity under the applicable rules. A run by the visitor is not automatically a game-ending score. Read the top-or-bottom marker and the current margin before reacting. In the bottom half, a winning run can end the game through a walk-off. That creates a different tension from the top half, where the visitor is trying to establish a lead that its defense must still protect.
Avoid a universal explanation for every replay
A postseason replay may begin an extra inning with empty bases, and an older regular-season game may reflect a different historical framework. Use the date and event type to interpret what you see. For a practical exercise, note the starting runner, outs and score at the beginning of an extra half-inning, then follow the sequence to its end. The exercise shows the rule's effect without assuming that every runner at second was automatically placed there. Some will have arrived through ordinary play.
Useful answers
Is the automatic runner used in MLB postseason extra innings?
No. The official MLB explanation distinguishes the regular-season arrangement from postseason play. Confirm the competition stage before applying it.
Does a run in the top of an extra inning end the game?
No. The home team normally still has its batting opportunity. The half-inning marker is essential when interpreting an extra-inning lead.