It's one of the many twists and turns that came with Interleague Play throughout the 2013 season, a move necessitated by the switch of the Houston Astros to the American League to provide a balance of 15 teams in the AL and 15 in the National League.
This year's Interleague story started with the first Opening Day matchup of Interleague foes: the Angels visiting the Reds. It continued with the earliest use of the designated hitter by a NL team, when the Mets visited the Twins in mid-April. And soon, it'll be two here and two there, with a bunch of teams traveling to the other side of the city or state -- and some farther -- in between.
With all that and a future of Interleague games going on right into September throughout the stretch run, this year's Interleague story has yet to be fully written.
Katy Feeney, Major League Baseball's senior vice president for club relations and scheduling, has been in charge of developing the MLB schedule for years, and she said it's too soon to tell just how well this groundbreaking iteration of Interleague Play is going to play out.
"It's early," she said. "I think over the course of a season, we'll know more. I think it will be more telling as we get to the end of the season."
For some, if there's one thing that stands out already about this uncharted territory for Interleague Play thus far, it's that it really hasn't stood out at all. AL pitchers are hitting or NL hitters are playing DH on any given day, and life goes on.
"I think more than anything, we've had Interleague so long now so we've gotten used to it, so you don't really see it as being a big deal -- the fact that every day somebody's playing an Interleague game," said Giants manager Bruce Bochy.
Of course, not everyone sees it that way. For an AL manager like the Twins' Ron Gardenhire, the change in Interleague Play has potential pitfalls that haven't presented themselves yet.
"There's going to be complications with it," Gardenhire said. "Teams fighting in the last month and you're going to play Interleague, and you're an American League team and your pitchers are having to hit, you have to change your whole game in September in a pennant race when you're one game behind a team or something. That can be tough."
That could be the case, for instance, for the Detroit Tigers, who wrap up the regular season at Miami, meaning their pitchers will have to hit and their designated hitter will have to sit in what could be a crucial three-game series.
For Gardenhire, the more traditional (if you can use that word about something born in 1997) brand of Interleague Play -- kept to a certain segment or two of the season -- was preferable.
"I liked it better when, if you're going to do it, do it in the middle [of the season], like they were and leave them there, rather than all over the place," Gardenhire said. "I know there are reasons, but at least we knew how to prepare for it. We're going to play in National League parks, we're going to play in two cities, we let our pitchers hit, [prepare them] a couple weeks before and then we would be done. You wouldn't have to deal with it until the World Series."
But as Feeney knows, that old way of doing things just wasn't going to fly this year. The decision was made to shift the Astros to the AL West and create six five-team divisions, thus balancing the leagues with an equal number of teams for the first time since 1997. Simply put, the schedule would have to be considerably altered. This particular iteration was agreed to by the Commissioner's Office and the MLB Players Association, but the exact format is not written in stone for 2014, or beyond. This year's slate includes 16 Interleague games for each team, one more than in previous seasons.
Feeney said 15-15 scenarios have been studied for many years, with different setups providing increased or decreased Interleague Play, increased or decreased intradivisonal play and other variables.
But there are certain constants in play as well.
"With 15-15, you've obviously got odd numbers everywhere you look," Feeney said. "Besides having Interleague every series, you also have somebody out of their division every series, and there are those periods when you might want to be within your division, which is impossible to do."
Next week's rivalry home-and-home series, in one sense, could be seen as a way to kick off the summer with a format that gives a little taste of the postseason in May for the first time -- two teams going home-and-home consecutively. In another sense, Feeney says it was a key way to get the unprecedented schedule to fit, since there had to be a "squeeze week" -- one week in which every team plays three series -- and the rivals were going to play a pair of two-game series at some point, anyway.
"It sort of developed as a way to fit the prime rivals into the schedule, and since most of the prime rivals -- not all of them, so it's not easy for everyone -- are close, it doesn't involve difficult travel for most teams," said Feeney.
While that's certainly true of Yankees-Mets, Giants-A's and the like, the Braves and Blue Jays will have a bit more travel, as will the Padres and Mariners on the West Coast, and the D-backs and Rangers -- who double up on Monday and have Tuesday as a travel day across two time zones.
But this world of scheduling is always a balancing act. There is, for instance, the matter of rescheduling Interleague rainouts for teams that otherwise wouldn't cross paths again this year. On the other hand, there is more balance in the Interleague foes division rivals face during the season.
How this year's unprecedented Interleague schedule pans out remains to be seen, and Feeney knows there will be a little bit of everything ahead. Fond of saying her job is to make sure everyone's unhappy about something -- and she's usually right -- the keeper of the Major League schedule knows only one thing for sure.
"With anything in a schedule, you will find benefits and obstacles," Feeney said.