The center of every sport

You’ve probably heard of six degrees of Kevin Bacon: the idea that every actor is a few movies away from him. Sports has a version of this, and it’s built from rosters. Two players are linked if they were teammates. Two players who weren’t are linked through someone who played with both, and so on.

So which player is the true center of a sport, the one with the shortest average chain to everyone else who ever played it? We measured it, using every roster in Teammate Chain.

The answers

The pattern is clear. The center isn’t the best player, or the most famous. It’s someone with a very long career who moved around a lot, and who played in the middle of the sport’s history, so he can reach the old-timers and the newcomers equally well.

Baseball: Tommy John

Tommy John is best known for the elbow surgery named after him. He might deserve to be known for this too. He pitched for 26 seasons, from 1963 to 1989, missing one to that surgery. He pitched for the Indians, White Sox, Dodgers, Yankees, Angels and A’s, and shared a roster with 555 different players.

His career sits right in the middle of baseball’s timeline. His early teammates had played with stars from the 1940s, and his late ones were still playing in the 2000s. From him, the whole history of the sport is close by. Here’s how far every one of the 21,482 players in the data is from Tommy John:

The farthest anyone gets is 7 links. Everyone that far out debuted in the 1870s, 1880s or 1890s, when careers were short and rosters were small.

Why the other sports are tighter

Baseball’s numbers are bigger because its history is longer. The data goes back to 1871, while the other sports start much later in our data. Fewer decades means fewer generations to cross. A shorter history also explains why the hockey center is so close to everyone: almost every player since the 1967 expansion is within four links of Jaromír Jágr, whose NHL career ran from 1990 to 2018.

Football’s center is a kicker, Adam Vinatieri. Kickers play for a long time, and a long career on big NFL rosters adds up to a lot of teammates. Basketball’s is Vince Carter, who played 22 seasons for eight teams.

What it means for Teammate Chain

If the center is only a few links from everyone, then any two players are at most a few links from each other through him. That’s why even the strangest Teammate Chain pairing is never far apart, and why the shortest chain usually needs just two or three players in the middle. When you’re stuck, think of players like these: long careers, lots of teams, right in the middle of the two eras you need to connect.

For the full list of well-traveled players, see the players with the most teammates.

How we counted

Two players are linked if both appeared for the same club in the same regular season. For each sport, we took the 300 players with the most teammates and measured the average shortest chain from each of them to every other player, then picked the lowest. The data covers every MLB and major-league season since 1871; every NBA season since 1946-47 (BAA included); every NFL season since the 1970 merger; every NHL season since the 1967 expansion; Europe's top five leagues since 1963-64.