All those players are created with no real life stats when they are loaded in 1878.
Ned Williamson (id 359)
The Only Nolan (id 361)
Russ McKelvy (id 354)
Jim McCormick (id 353)
All those players began their professional career with the Indianapolis team in 1878.
https://www.baseball-reference.com/teams/IND/1878.shtml
Also since the Indianapolis stats aren't listed: John Clapp (127) and Orator Shafer (224) miss season according to history and Art Croft (238) is retired.
Obviously Jimmy Hallinan (84), Joe Quest (59), Fred Warner (293), Tom Healey (350) and Candy Nelson (150) 1878 statistics with Indianapolis don't show up.
Just want to add, if it does a difference for you, that I play with no minor leagues, so only the players who played in the major league show up.