In 49 plate appearances spanning 17 games with the Mets in 2014, the 26-year-old den Dekker was hitting .156 with a .224 OBP.
Nieuwenhuis, 26, hit .222 with a .286 OBP in 21 plate appearances with the Mets earlier this season.
In Triple-A Las Vegas, Nieuwenhuis was performing fairly well, hitting .272 with a .318 OBP to go along with 10 home runs and 30 RBI.
While Kirk Nieuwenhuis is a somewhat better hitter than Matt den Dekker, today’s move is pretty much a lateral one.
With center fielder Juan Lagares likely just days away from returning from the disabled list, Nieuwenhuis’ promotion may be a temporary one – unless the Mets swap out Eric Campbell when Lagares is activated.