Hey, I just found this on Carl's website.
90 degrees or 2SF (2 steps fair) for calls at first
If you’re already an umpire, you have been taught to strive for the 90-degree angle on calls, particularly for plays at first base.
Back in the late 80s, major league umpires began moving just inside the line. Lots of people thought it was simply the laziness of the behemoths in blue. For example, here’s what I wrote about that practice in my Referee “Doing It†column for June 1988:
If you or I tried to get away with those 15-degree, two-short-steps-inside-the-line angles, our coaches would fire us for not hustling, even if we did make the right calls.
At the time, I had never heard of 2SF, but I described it perfectly: “two short steps inside the line.â€
I must admit that was an ignorant remark. Research shows that 2SF is a great place to be for calls at first: You can help on batter-interference, you rarely get blocked by the fielder’s foot, and you’re in perfect position for swipe tags and the pulled foot of the first baseman. You must be alert: Here, you keep your eye on the runner first and the ball second.
Everything is great – in a four-man crew. Now take away two. What happens when the defense overthrows the ball but it remains in play? Your perfect position for a call at first dissolves as you try to charge into the diamond, looking for some kind of view of the looming play at second.
You’ll never get there. Not even the swift-as-deer Triple A umpires are that fast. I recommend: Save 2SF for 3- (221) and 4-man (100) crews. Get well out onto the dirt in your typical two-man setup