I drove past the Astrodome last week, seeing the old stadium for the first time. Now dwarfed by the adjacent Reliant Stadium, it brought back memories of 1-0 victories thrown by great Houston pitchers like Nolan Ryan and J.R. Richard.
Through most of its history, the Astrodome was an awful place to hit a baseball. Jose Cruz had the misfortune to play there in the 1970s and 80s. Had Cruz played in Fenway Park or Wrigley Field back then, he may be remembered as one of his era’s greatest hitters.
Cruz hit 59 career home runs in his home parks and 106 in road games. Although he started with Cardinals and ended up with the Yankees, Cruz had 83 percent of his career plate appearances for the Astros.
During his peak from 1976 to 1986 – when he played exclusively for the Astros – Cruz had a 128 OPS+ according to BaseballReference.com. Since this metric adjusts for both the league average and a player’s ballpark, the Astrodome’s negative impact gets stripped away. Cruz ranked 24th in OPS+ among players with 2500 plate appearances from 1976-86, finishing in a group of more heralded players like Dale Murphy (129 OPS+), Cal Ripken Jr. (129), Kirk Gibson (128), and Dave Parker (128).
In that same timeframe, Cruz hit 100 homers and stole 250 bases. Only Andre Dawson, Rickey Henderson, and Davey Lopes joined him at those levels. Cruz reached base 2412 times, more than all but five other Major Leaguers from 1976-86.
While there are no stadiums like the Astrodome today, Safeco Field and PETCO Park have a comparable impact on offense. Although we now have tools that few knew about during Cruz’s playing days to adjust for run context, they still get limited attention.
Ballparks have a huge impact on statistics, yet many fail to take this into account in solving the value puzzle. Examining park effects is vital for not only showing a player’s true performance level, but where his career is headed.