Acta gets mentioned because everyone assumed the Nationals would lose 120 games this season. The Nats were stripped down, placed in a deep rebuilding mode, and the offense has indeed been dreadful this season. The pitching, particularly the bullpen, has been better than expected, though, and after a 9-25 start, Washington has played better than .500 baseball. The Nationals will still lose somewhere around 95 games but haven't been a complete embarrassment.
That's your manager-of-the-year field, and I would point out that it's an awful lot easier to win baseball games when your pitching comes through - as it has for the other candidates - than when it disappears, as it has for Manuel.