The Mets' offense has been in a brutal slump for a few weeks now. For the season, the team ranks poorly in most offensive metrics, and the struggles—particularly the recent ones—have been widespread. So making a change with a couple of non-everyday players might not make that much of an impact, but it's probably worth giving utility-man Alex Castellanos, who has primarily played in the outfield but has also played the corner infield positions a bit, a shot in the big leagues.
All hitting stats are inflated in the Pacific Coast League and even more so in Vegas, but Castellanos has hit .302/.374/.589 with 13 home runs and a 156 wRC+ for the 51s. He's 28 years old and hits right-handed. He hasn't done much in a couple brief stints in the big leagues, but things are going well now, and maybe he could give the Mets a slight boost on offense.
If he were to get called up, Castellanos would presumably replace Eric Campbell on the Mets' major league roster. Campbell has hit just .167/.282/.258 with a 59 wRC+ in 156 plate appearances for the Mets this year. Campbell hit really well in Vegas earlier this year, too, and there's no guarantee that Castellanos would be better at the major league level. But it might not hurt to try.