The No. 2 hitter, according to the great "The Book: Playing the Percentages in Baseball," is one of the most essential spots in the lineup. It comes up with about as many RBI chances as the No. 3 spot, but obviously comes up more often. Thus, while historically the idea is that you should bat your best hitter third, in fact he should hit second or fourth (where there are even more chances to drive in runs but of course fewer plate appearances).
Neither manager, Joe Girardi nor Ron Gardenhire, made a big deal of the move, and in each case it's not likely to remain in place for long. But there's some real sense to both decisions. Cano and Mauer are both all-around hitters who can get on base for the men behind them and drive in the guys in front of them. And the one worry about batting a star hitter second in the National League, that he's only two spots behind the pitcher, doesn't apply in the American League.
"I want [Mauer] to bat first, second and third, but I can only bat him in one place, so we chose second," Gardenhire said.
Gardenhire pointed to an old philosophy that Tony La Russa was fond of: having power early in the lineup to get a pitcher's attention. La Russa often referred to having "damage" in the two-spot, a place where he put hitters such as Jim Edmonds and Larry Walker. Those hitters, of course, were both also high-OBP men, as are Cano and Mauer.
Girardi also noted that moving Cano to second, with Kevin Youkilis third, breaks up a run of left-handed hitters in the Yankees order.
"It's just to try to not make it so easy on the other team," he said.
While the fundamentals, getting on base and hitting for power, are most important, a secondary consideration for a good No. 2 hitter is avoiding the double play. It's assumed that your leadoff man is going to be getting on base at a pretty good clip, and that the batters in the 3-4-5 spots are the sorts who might turn those baserunners into runs. So a hitter who has a proclivity to hit into twin-killings is a bad fit for the two-hole.
That's actually one area where Cano and Mauer fall a bit short. They both hit into their share of double plays, though neither is an extreme DP threat. It helps that they're both left-handed, making it a smidge easier to get to first base in time.
In the end, both Mauer and Cano will likely be hitting third (or perhaps fourth) before too terribly long. But it's not as odd as some people might think to have them hitting in the No. 2 spot for at least a little while.