Which Playoff Team Has the Most Former Players from Your Favorite Team?

When your favorite baseball team misses out on the playoffs, October offers a brief free-agency in fandom. Do you temporarily switch to root for a loved one’s team, or choose to root against a rival?

For me personally, I want former Rockies players to do well. It would be fantastic to see DJ LeMahieu lift the Commissioner’s Trophy, even if he’s now wearing the wrong color of pinstripes.

But do I really have to root for the Yankees? I wanted to see if I had any other option — to see if there was any other playoff team with more former Rockies.

I started with FanGraphs data showing player totals from every season going back to 2001 (CC Sabathia is the player on a 2019 playoff roster with the earliest debut, having come on April 8, 2001 for Cleveland). I also defined “playoff roster” as only including players who made an appearance for a playoff-bound team in September of 2019, so if someone hasn’t seen the field in the last month, they’re not counted here.

I didn’t want a player with only 15 ABs to have the same weight as a player with 1,000 at-bats, so I used each player’s “appearances” for their former clubs (plate appearances as a batter plus total batters faced for pitchers, including both regular season and playoffs).

The results confirmed that, yes, by this metric I’m now a Yankees fan. Thanks to LeMahieu, Adam Ottovino, Tommy Kahnle, David Hale, and Mike Tauchman, rooting for the Yankees means rooting for the most former Rockies who are playing in October. These five players add up to 6,283 plate appearances and batters faced while in a Rockies uniform.

For fans of other teams, the choice isn’t so obvious. Detroit fans might be pulling for their former ace, Justin Verlander, to win another championship with Houston. But he’s the only former Tiger on the Astros roster. The Nationals have Max Scherzer, Anibal Sanchez, and Fernando Rodney playing recently, though those three combined to make fewer appearances for the Tigers than Verlander did on his own.

There are two teams that are now watching a lot of their former players play for their more-successful divisional rivals. The Mets have the most former player-appearances on the Nationals, and the Blue Jays have the most on the Yankees. But other than that, there are no close rivalries among the pairs of teams.

Feel free to peruse the list and make any suggestions for improvements:

* ARI –> WSN
* BAL –> ATL
* BOS –> MIL
* CHC –> LAD
* CHW –> TBR
* CIN –> OAK
* CLE –> NYY
* COL –> NYY
* DET –> HOU
* KCR –> MIL
* LAA –> WSN
* MIA –> NYY
* NYM –> WSN
* PHI –> NYY
* PIT –> TBR
* SDP –> MIL
* SEA –> NYY
* SFG –> MIN
* TEX –> MIN
* TOR –> NYY

My Python code for this analysis can be found here.