Hey, Robey- when I see you at the Westerville tournament I'll let you borrow my rule book and you can show that to the parents who say you're wrong!
Or you can send them to talk to me. ;D
And, yep, the obstruction rule applies equally to ALL bases.
Softballump, as I read your further comments and we get deeper into this thread, I get the feeling that our opinions on straddling the base are closer together than it first seemed.
Straddling the base MIGHT get you an obstruction call, if the action actually impedes the fielder. If it doesn't, then you can't have obstruction.
I can envision a couple of plays to illustrate this.
1) Play at plate. Catcher straddles the plate awaiting the throw. The runner is still well up the line and running full speed. The runner never breaks stride or alters her path. The ball arrives well ahead of the runner and she is tagged out.
Most likely not obstruction on that play, depite the catcher at some point straddling the plate. The runners progress to the plate was not impeded.
2) Same play, but the runner is much closer to the plate and must begin sliding before the catcher receives the ball. She is then tagged out.
Probable obstruction, as the runner had to alter her path- she was forced to slide- before the catcher got the ball. If the catcher was not standing over the plate without the ball, the runner would have the legal option to remain on her feet.
3) This one I'm sure we all agree on.
Shortstop straddles second base without the ball as the runner tries to round the bag and go to third. The fielder being in the way either bumps the runner, forces the runner to go out around her or stop unnecessarily at second.
I bet that we would all consider that one to be obstruction.
Straddling the base MIGHT be considered blocking the base. This could possibly vary from play to play.
Straddling MIGHT lead to an obstruction call if it is both deemed to have blocked the base AND impeded the runner trying to reach the base.
Blocking a base without the ball is in and of itself not illegal.
Blocking a base without the ball AND impeding the runner is illegal and a perfect example of obstruction. Both things have to happen to get that call.
From a coaching standpoint, the safest way to avoid an obstruction call is to teach your fielders to set-up just out of the basepath to receive the throw, then to move into the path for the tag. The sequence would be- receive, block, tag.
If they do it the other way around- block, receive, tag- then they are opening themselves up for an obstruction call.