Possibly obstruction. Hard to tell from the picture, but I would ask these questions:
- Did the sliding runner contact the catcher before she reached the plate? Obviously, the catcher does not have possession of the ball at the moment the picture was snapped. If a runner is sliding in a legal manner, in normal attempt to reach the base, and contacts a fielder not in possession of the ball, then that is obstruction.
That one is pretty cut and dried- the fielder either had the ball or she did not and there was either contact or there was not.
- This one's not so cut and dried and involves more umpire judgment.
A runner attempting to score does have the option of remaining on her feet and running straight across the plate. If the catcher's positioning (ie: blocking the plate, without the ball) forced the runner to slide when she otherwise could have reasonably remained on her feet and run straight across the plate, then her path has been altered. That is obstruction.
Even if this is ruled as obstruction, that call might not affect the outcome of the play. If that obstructed runner touched the plate before being tagged, the obstruction is moot. She is still safe and the ball is still live. If she was obstructed, then tagged out before reaching the plate, then the ball is dead and the runner is awarded home.
In high school and ASA softball, it used to be that fielders could legally block the base without the ball, if they were so positioned to catch a throw in their immediate vicinity. That is still the rule in NCAA softball. But about five years ago high school and ASA rules changed this.
If the above picture was from a college game, this definitely would not be obstruction. In most all amateur codes below NCAA, it probably is.