What is the ruling if F4 is in the baseline and R1 jumps over him?

In this scenario, the determination that R1 is out due to jumping over F4 is based on the rules of obstruction and runner safety. When R1 makes the decision to jump over F4, if it’s deemed that R1 did not make an effective effort to avoid contact or that jumping was not an appropriate response to the situation, the outcome can lead to an out call.

The key aspects of the rule involve understanding that a player must avoid contact with fielders when possible, and the runner's action of jumping may be interpreted as an attempt to avoid the fielder rather than an active play to get to the base safely. Therefore, if the jump proves to be a maneuver that results in R1 being out (for instance, if he lands improperly or interferes with F4), the ruling will favor the fielding team's rights to make a play on the runner.

This ruling aligns with the enforcement of safety and proper competition standards in the game. The nuances of each play can reflect on comparable scenarios in which a runner may be called out for making a less-than-appropriate response to the presence of a fielder.