X different Opening Day Starting Left Fielder in X Seasons (since 1914)
Baseball-Reference takes us back until 1914 and while Retrosheet provides starting pitchers in their game logs, it doesn't have that for other positions.
The 19-year run by the Browns/O's is the longest of any position. Oakland gave it a good run (going all the way back to Ben Grieve!) but Yoenis Cespedes snapped the streak last year. With their winter pickup of Justin Upton, the Padres probably extend their current streak to 11 (Ryan Klesko, Eric Young, Jose Cruz, Paul McAnulty, Chase Headley, Kyle Blanks, Ryan Ludwick, Jesus Guzman, Carlos Quentin, Tommy Medica). The Yankees had a dominant stretch from 1994-2003 while left field was a revolving door. If not for Joe Medwick's three-year run from 1941-43, the Dodgers would have had a 21-year streak.
Here's the full list of left fielders from the teams shown above. Some interesting names here include the one-armed Pete Gray, who played 77 games for the Browns in 1945. A few players I didn't include to see in left field are Carlton Fisk, Rafael Palmeiro and John Kruk. There's also Leo Posada (uncle of Jorge), the colorful Frenchy Bordagaray and 1946 Dodger Dick Whitman (or is it Don Draper?).