21 HR by Chris Carter in 169 AB's

Without having real-time access to a comprehensive baseball database, I'm unable to provide a specific list of all professional players who hit 20+ HR in under 200 AB's since 1990. However, I can suggest how you might find this information. If you want to obtain this statistic for Major League Baseball (MLB), you can turn to the official MLB website, which offers a plethora of statistics about seasons, players, teams, and specific game details. Alternatively, you might use stat websites like Baseball-Reference or Fangraphs, where you can apply filters or use the Play Index and splits to find specific player accomplishments. For international or minor league statistics, this can be a little trickier because not all leagues keep detailed statistics online. You can use sites like Baseball Reference's Bullpen and leagues' individual official websites (if available) for the most accurate information. Remember, hitting 20+ HRs in under 200 AB's is relatively uncommon due to the high level of skill and power it requires, so there might not be a long list of such instances.