I felt that one of the keys to my 1900s team was having Pat Moran and his A+ arm at catcher. He has 500+ PA/162 for only $4.0 million. Opponents stole successfully only about 54% of the time when he was behind the plate. I tried to play Nig Clarke and his stronger bat only against teams that didn't run much.
Could one of the reasons for the 1940s success be the relatively strong normalized hitting? TW, Joe D, and others have some very nice seasons that aren't super expensive. '48 TW is now $9.53 million and he produced .355/.449/.543 in Sportsman's Park III to help me win. Also, the better 40s pitchers tend to have low BB/9 and HR/9 (compared to post WW2 pitchers) which helps them to be more competitive. When you add in low K/9 for most of these pitchers, their salaries are very reasonable. With the better 20s and 30s pitchers generally not performing in the sim as they should, it essentially made the NL a race between the 00s, 10s, and 40s.