I used the 2-catcher and 3-catcher considerations in my lists for Bresnahan and Bennett, since they were both pre-1925 catchers, and catchers weren't as durable back then. However, between 1933 and 1940, we usually had four catchers per year who are played at a 20-WS level (whether in the majors or in the Negro leagues); occasionally we had just three. By the 1930s, we finally had enough durable catchers for 20 win shares to be a good cutoff for an "All-Star-type" season for a catcher.--I'm also not sure its accurate to say Lombardi had only 2 All Star type seasons. Basically the best 2 catchers in the 8 team leagues and best 3 in expanded leagues could be called legitimate All Star caliber players. Most years there were not that many catchers with 20 WS. That figure might be reasonable at other positions, but a lower baseline might be more appropriate for catchers.
--I'm not arguing that Lombardi should make the BBFHoF. He isn't on my ballot and probably never will be. I am saying that the standards applied to other positions may not be fair to catchers.
Ideally, the definition of an "All-Star-type" season shouldn't depend on how many other players are having good seasons that year (I haven't figured out how best to do this for pitchers yet). During the 1970s, the number of catchers having 20+ win shares could be anywhere from two to eight. Sometimes a league has a dearth of good catchers; 14 win shares were good enough to be the second-best AL catcher in 1950, while the fourth-best catcher in the NL that year had 19 win shares.
However, looking at post-1925 catchers, seven seasons with 20+ win shares seems to be the cutoff area, as Freehan, Hartnett, and Ivan Rodriguez all have seven such seasons. This is a slightly lower baseline for catchers, as I've found that eight is the approximate lower limit for other positions.
I haven't posted the Keltner List for Quincy Trouppe yet, but he does have seven seasons with 20+ win shares, and he might have had more if we had statistics from his seasons with Bismarck. From 1939-1943, Trouppe was better than any major league catcher, and there are only three instances in that time span where a MLB catcher had a higher single-season win share total that Trouppe's projected MLE total. However, as we all know, Trouppe wasn't even close to being the best catcher in baseball then.
The competition Lombardi faced for best catcher in the NL (or in the majors) was relatively weak in part because the two best catchers in baseball were prohibited from playing in the major leagues.