R1 attempting to steal 2B. F4 standing directly in base line between 1B and 2B about fifteen to twenty feet away from 2B bag. R1 and the ball thrown by F2 arrive at about the same time to F4. F4 catches throw at the same time that R1 is colliding with F4. R1 falls down and is tagged out. Which player is obligated to do what in this situation? Is R1 expected or required to run out of the base line and around F4 who is set up to catch throw from F2 or is F4 expected or required to stay out of base line without the ball? F4 wasn't near 2B but was blocking base line to 2B. R1 probably slowed down a little running to 2B because of F4 being in base line. Is a player blocking base without ball when player is not close to base but is in direct path of bases?

"R1 probably slowed down a little running to 2B"

Combine that statement with a fielder in the basepath without the ball... and that's all you need for obstruction.

"Is a player blocking base without ball when player is not close to base but is in direct path of bases?" That is not obstruction unless the act of being in the basepath without the ball caused a runner to alter her path.