I took a quick look at Ross Barnes' 1873 team, the Boston Red Stockings, and at the National Association that they played in. A few differences between that kind of baseball and the more modern variety do sort of jump out at you from the stats.
https://www.baseball-reference.com/leagues/NA/1873.shtmlThe Red Stockings had a team batting average of .340. They scored 739 runs in 60 games. That's 12.3 runs per game. Almost all of their 60 games were started by Al Spalding, who posted a 41-14 record, .745 w/l pct.
The team allowed 183 earned runs in its 60 games, resulting in a 3.07 ERA. But they allowed 460
TOTAL runs, which means that 277 of the runs they allowed (more than 4 per game) were unearned. The team's fielding average was .836, which was a shade better than the league average of .831. This FA is understandable because—if I understand correctly— the first baseball glove weren't worn until two years later, in 1875.
Overall, the majority of runs scored in the National Assoc. in 1873 were unearned: 3580 total runs, 1353 earned runs. League average ERA in 1873 was 3.40, but league average runs scored per game, by each team, was 8.99.
In 1873, the pitcher stood 50 feet away from the batter, throwing underhand to a catcher who had no glove, and therefore couldn't catch anything really fast. The batter could call for a high or low pitch and it took eight balls to make a walk.
To me, that seems like a fundamentally different game—and for me the analogies to slow-pitch softball are real.
That doesn't necessarily mean that players pre-1894 should be excluded, because one of the challenges of managing in SOM is making an effective team out of players from different eras. But it does give one pause.
In order to understand what it means to integrate players from the pre-1894 era into SOM, we need to take a quick look at the normalization rules SOM has applied to position players and to pitchers. First of all, regarding pitchers, SPs can't pitch more often than every 4 days, so Charley Radbourn's best card is never going to reach the 678.2 IPs he produced while starting 73 games in 1884.
The position player normalization feature involves errors. In 1873, Barnes committed 75 errors in 60 games, including 56 at 2b and 19 errors at 3B. His FA was .857 at 2b and .759 at the hot corner. But his card rates him as a 1e30 at 2B. Why? According to the SOM rules, pre-1920 fielders have been normalized to 1920 fielding levels, because otherwise (and I'm paraphrasing here) the results would just be too crazy. See:
http://365.strat-o-matic.com/help/hittercard This normalization has an extreme effect on a player from Barnes's era. Without the normalization, Barnes might be rated in SOM as an 1e175 at 2B instead of 1e30, since he'd likely have committed 175 errors at 2b—or more—in 162 games. A 1e175 error rating, while accurately reflecting the conditions of his time, would have a radical impact on Barnes's price and usage, and it would likely render him unusable against more recent players.
So my discomfort with adding bunches of players from pre-1894 era is partly the effect of SOM's extreme normalization of the radically different fielding environment. Barnes has the advantages of being a player who could bunt fair-foul, hit under-handed pitching he could call to be high or low, and bat against fielders w/o gloves, all of which helped him hit .431. But he doesn't suffer the disadvantages of an environment that produced huge numbers of errors.
That doesn't mean he shouldn't be in the set, but it does help to explain my own discomfort with adding a lot more players from this era.