Den dekker, Recker, and Carson will take the places of Marlon Byrd, John Buck, and Matt Harvey on the roster. Byrd and Buck were traded to the Pittsburgh Pirates earlier today, while Harvey has been placed on the 15-day disabled list with a partial UCL tear.
Carson has had an underwhelming season to say the least. In 43.1 innings at Triple-A, he posted a 4.15 ERA with a 36/19 strikeout to walk ratio and a 1.52 WHIP. He was significantly worse for the Mets in 18 big league innings earlier this season, posting an ERA of 8.5 and allowing seven homeruns, while posting an ugly 7/7 strikeout to walk ratio. He stands to be the third left-hander out of the pen.
Recker posted a .193/.244/.385 line as Buck's backup for most of the season and figures to back up Travis d'Arnaud for the rest of the season.
Den Dekker represents the most intriguing of the three call-ups. In 179 ABs for Triple-A this season, den Dekker hit .296/.366/.486 with eight homers and six doubles. More importantly for him, he managed to cut his strikeout rate this year (22.8%) significantly down from 2012 (28.4%). Den Dekker is widely regarded as the best center-fielder in the organization, even better than Juan Lagares, and it's not yet clear how much playing time he will get.