“OMG” has raked in over 2 million on-demand audio and video streams in the U.S. through Oct. 10. It’s a pop hit like many others: An ascending chorus, an addictive hook, a warm rhythm. But “OMG,” performed by New York Mets infielder Jose Iglesias, has become the perfect anthem for the team’s unlikely playoff run.Since its release on streaming platforms in late June, “OMG” has become a hit for a Mets team with a fun-loving vibe, embraced on and off the field.