MLB teams must designate every player on the active roster either as a pitcher or a position player and are limited to carrying 13 pitchers on the active roster (14 pitchers from Sept. 1 through the end of the regular season).
Those designated as position players are unable to pitch unless it is extra innings or their team is ahead or trailing by more than six runs when they take the mound. Teams can also designate players as two-way players if they meet certain criteria. Two-way players are able to pitch in any situation but don't count toward the active roster's pitcher total.
Players qualify for the two-way designation if they have met both of these conditions in either the current or previous MLB season:
• Pitched at least 20 Major League innings
• Played at least 20 Major League games as a position player or designated hitter, with at least three plate appearances in each game