In 2011 he pitched for the A ball Brooklyn Cyclones going 4-6 with a 3.32 ERA pitching as a starter. The next year he was converted into a reliever where he pitched at A ball St. Lucie & A Ball Savannah. In 2013 Walters was promoted to AA Binghamton where he became the AA Mets closer, saving 38 games while going 4-3 with a 2.09 ERA. He also struck out 60 batters in 56 innings of work finishing up 52 games.
In 2014 he made the Mets Spring Training roster, seeing some early March action. He was then moved up to AAA Las Vegas for the season, closing six games for the 51s. He pitched in 23 games before needing Tommy John surgery ending his season.
Overall Walters was tied for second on the club with Gonzalez Germen in saves, one behind bullpen leader Vic Black (7 saves). He went 3-3 with a very high 8.86 ERA.
In 2015 he returned late in the season, after a quick recovery. Walters started out pitching six games in the Rookie League, then six more games with the A ball St. Lucie Mets going 1-0.
He was then pushed up to the AA Binghamton Mets (17 games), pitching well, where he was 2-0 with 1.96 ERA, striking out 21 batters with 3 walks in 18 innings.
In May 2016 he was designated for assignment to make room for James Loney on the roster. Walters spent all of 2016 at AAA Las Vegas going 4-3 as a reliever. He had one save, struck out 48 walking 28 in 65 innings of work in 56 games. At the end of the year he elected free agency.