I am very curious about this play. As a slapper, it seems that it would have been nearly impossible for her NOT to be left of the line at that point during the base-running, given that the first baseman was standing precisely where she would have begun to cross over to the right side. Also, maybe I was seeing things, but didn't it look like she was trying to avoid a collision with the first-baseman at the last second, while the latter deliberately (reflexively? defensively?) shoulder-checked her anyway, knocking her to the ground, even though she (the first-baseman) was in no position to make a play? If there can be no obstruction calls as long as the runner is on the left side of the baseline, what's there to keep any fielding team from using this tactic to neutralize the quicker and more aggressive slappers (i.e., sending the first baseman to box in the runner to the left of the line and possibly instigate a collision at the cross-over point)? If a slapper has to make a sharp right turn to go around a charging first baseman on the "good" side of the line, she would forfeit a lot of the speed advantage afforded to her by slapping in the first place.
Just trying to learn something from this...
Going on memory I believe that the Sooner runner was pretty far up the baseline when the collision happened. It appeared to me that she had time to get back into or near the running lane...enough so to avoid contact anyway. The slapper HAS to take several steps up the line on the field especially as far in front of the plate that contact was made with the ball while batting. But this ball was slapped up the first base line. The runner almost had to realize early on that the first baseman was moving into position to field the ball. A fielder is entitled to field the ball without interference from the runner. In my opinion, the Sooner slapper had plenty of time to avoid contact but didn't.
As far as setting up fielders to obstruct runners as the run up the line...I don't know. I've never seen it done. It would seem to me that they should be more concerned with making legitimate fields and throws.