When it comes to teamwork in baseball, the immediate duo that comes to mind is that of the pitcher and catcher, who must work in concert together on every single pitch. But a catcher will work with several pitchers a day, a dozen in a week and perhaps 20 or more over the course of a season. He might work with a single starting pitcher only four or five times in a month. It is his duty to lead an entire staff, rather than work with a particular pitcher.

Compare that to the middle infield pairing, perhaps the most important combination of teammates on the field. Day in and day out, the second baseman and shortstop must work together seamlessly for nine innings. They have to know where the other will be positioned, and learn each other’s rhythm, strengths and weaknesses. They have to trust that their partner will back them up on missed plays, and to know without looking that they will be there when they field a grounder and turn to start the double play. It is arguably the most important combination in a game, not just because of what they can do for one another—it is, obviously, difficult for either to turn the classic 6-4-3 without the other—but for the rest of their teammates. Ask any pitcher who has had a hard-hit ball turn into an inning-ending double play: the middle infield duo can make or break a game.

It’s rare that a team can find two quality players to fill that partnership, and rarer still that they can keep them together for several years. Today, we’ll count down the dozen greatest double-play duos in modern MLB history. Sorry, Tinker & Evers: this list doesn’t go back further than World War II, before which baseball was a markedly different game. To qualify, the pair had to be teammates for at least seven seasons, and to get their best, we’ll rank them by combined WAR (Wins Above Replacement, a catch-all stat that includes offense, defense, base running and ERA) during only their five greatest seasons together—during which they each had to be primarily playing the middle infield.