One of the most underrated players in Baseball's history has to be George Uhle, a Pitcher who spent most of his career with the Cleveland Indians and won an even 200 Games.
Historically speaking, one of the most important Pitchers in Latin America is Dennis Martinez, and he was also one of the most tenured.
Eddie Rommel played his entire 13-year playing career with the Philadelphia Athletics (1920-32), where he became one of the first masters of the knuckleball.
Rudy York was known mostly for his time with the Detroit Tigers, and it was there where he had his greatest success.