There was an interesting play in the Blue Jays-Yankees game last night. Toronto was batting in the bottom of the 4th with Edwin Encarnacion on first and none out. The batter Dioner Navarro hit a pop-up a little to the right of first base. On contact, Encarnation, who already had a lead, took a few steps towards second before realizing it was a pop-up. Mark Teixeira camped under the ball, right in the baseline, with Encarnation a few steps to his right. Encarnacion, seeing that he needed to return to the base, tried to go behind Teixeira, but as he did so Tex took a step back to line up the ball and the two of them got tangled up for a moment.
The first base umpire immediately called Encarnacion out for interference. However, this didn't stop Tex from catching the ball, and upon doing so the ump also called Navarro out. This produced a reaction from both benches, and to keep the story short, after an umpires conference they put Navarro on first with one out.
Did they make the right call? Let's look at the rules. First, the actual interference: It was pretty clear that Encarnation did not intentionally interfere with Teixeira; he was trying to go around behind when Tex took a step back to line up the ball and they had contact. However, Rule 7.08(b) states that a runner is out when "He intentionally interferes with a thrown ball; or hinders a fielder attempting to make a play on a batted ball", and the first paragraph of the comment following the rule makes it clear that "A runner who is adjudged to have hindered a fielder who is attempting to make a play on a batted ball is out whether it was intentional or not." So assuming that the judgement is that Encarnation did in fact interfere with Teixeira (the rule doesn't specify that the interference must have prevented an out from being made), then calling Encarnacion out was the right call. Note that the standard for interfering with a fielder trying to field a batted ball is different from a fielder trying to field a thrown ball. A batter must always yield the baseline to a fielder attempting to field a batted ball. However, fielders attempting to field a throw ball do not have the same right to occupy the baseline.
Second, what about that business with Narvarro? The "PENALTY FOR INTERFERENCE" clause at the end of Rule 7.09 states that in all cases of baserunner interference, "The runner is out and the ball is dead.". So the ball became dead when Encarnacion was called out for interference. This created a dilemma because it was prior to Teixeira catching the pop-up, and no outs can be made when the ball is dead. However, we have a precedent in regards to Rule 7.08(f), which covers the case of a baserunner being hit by the batted ball. As we all know, when this happens, the runner is out but the batter is not, and therefore the batter is awarded first base. The same thing was applied here: The batter Narvarro had not been put out when the ball became dead, and so he was awarded first base.
So how do you score this mess? Rule 10.09(c)(6) states: "When a runner is called out for having interfered with a fielder, the official scorer shall credit the putout to the fielder with whom the runner interfered, unless the fielder was in the act of throwing the ball when the interference occurred, [...]" Since Teixeria was not attempting to make a throw at the time he was interfered with, I left out the last part of the rule for brevity. Tex is credited with an unassisted putout. Since Narvarro reached base safely, it has to be scored as a fielder's choice. In the play-by-play it reads, "Narvarro grounded(!) into a fielder's choice, Encarnacion out at 2B(!), 3 unassisted." The "out at 2B" looks kind of weird; normally when a runner is put out trying to return to base on a fly ball, you say that he was put out at the base he was trying to return to. However, since Encarnacion was put out before the catch, I suppose it's bearable. The "grounded" part is really weird, but I guess the official scorer was afraid that the universe would reboot or something if he wrote "flied into a fielder's choice" (think about that).