Compare Joe Mauer to Sandy Koufax. Both were injured during their prime. Koufax quit after 12 years. His 3 years with Brooklyn, which were mediocre, were before his 9 best years. with LA, which were outstanding. Mauer kept playing after his injuries. Mauer player 5 years of mediorce baseball (10.4 WAR) after his best years.. I contend that Mauer's 10 best years as a catcher were so superior to any other catchers' 10 years (3 batting titles by a catcher- never been done before), that they compare to Koufax's 9 best years as a pitcher in relation to other pitchers. Did Koufax, as dominant as he was, ever do anything that no other pitcher has done before or since? No. I admit Koufax was dominant at his position for 9 years, but so was Joe Mauer for 10 years, in relation to all other catchers in the history of MLB. If Koufax deserves to be in the HOF (and he certainly does), then so does Joe Mauer (and he certainly does).
Koufax won 3 Cy Youngs in 4 years. Keep in mind that was AL and NL combined then. No one else won more than one when it was combined. Koufax won 5 consecutive ERA titles (3 of which were MLB ERA titles) and had six consecutive seasons where his FIP was MLB best. Pretty sure those are unique to him.