That's probably true for the levels most of us work. With the speed of professional players, it makes sense for pro to rotate, so that U1 can avoid any possibility of interferring with B1 rounding first.

And as we all know, mechanics typically filter down.

There used to be some pro rotation that varied based on whether it was an "obvious extra base hit." The problem occurred when one umpire read it one way ("obvious") and another read it another way ("not obvious").

The ONLY time the rotation helps is when a rundown happens between first and 2nd. However, other than annoying you, I don't see any harm in this rotation.

U3 can usually get to second and be set more easily than can U1 who has to pivot and watch the touch of first and for possible OBS. U3 can also adjust to take the play from the outside if needed.

Like many of the mechanics you can get it right using multiple ways.

I disagree.

As U1, I can focus more easily on the bag touch and on any possible obstruction. I can stay foul while doing this. While I can easily get to the cutout and be set for a play at second (I do it in 2-man all the time), U3 can do so much more easily.

U3 -- coming up to second is routine. He can do it the second he realizes he's not going out. He doesn't have to read whether it's the situation where he's staying home or one where he has to cover second. Ball's hit, he goes to second (after pausing and reading). As U3 on this, I'm taking the throw from the outside, if it makes sense depending on the angle of the throw, just like a play at the plate. I can't do that as the U1 pivoting in.

PU -- covering third is a piece of cake. He has no other job.

And U1 can very easily get to the point of the plate and take the play like any other play even waiting until the BR commits to third.

I just don't see why it's better to have one umpire do all of the heavy lifting on a play like this and let the other two umpires stand and (for the most part) spectate. These rotations do not put anyone out at all.

That said, other choices were used for years and could be used again someday. It's no big deal one way or the other -- the potential plays are covered.