According to Joel Sherman of the New York Post, Syndergaard is getting a second opinion from Dr. Neal ElAttrache in Los Angeles, and the three-month timetable is a conservative one.
The Mets announced Monday that Syndergaard had suffered a partially torn lat, which resulted in him being placed on the 10-day disabled list.
That revelation came days after Syndergaard refused to undergo an MRI.
Syndergaard was moved back in the rotation because of biceps tendinitis, but he didn't believe there was anything to be concerned about, per Abbey Mastracco of NJ.com: "I think I know my body best. I think I'm pretty in tune with my body that's why I refused to take the MRIs, I knew that there was nothing happening in there and that's encouraging to know. I'm ready to pitch on Sunday."
The 24-year-old righty ended up suffering a more significant injury, and the Mets are now without one of their biggest keys to success.
Syndergaard was named to his first All-Star team last season, and so far this season he is 1-2 with a 3.29 ERA, 1.10 WHIP and 32 strikeouts in 27.1 innings.
He is the latest big name for the injury-riddled Mets to hit the DL along with first baseman Lucas Duda, third baseman David Wright, shortstop Wilmer Flores, outfielder Yoenis Cespedes and starting pitcher Steven Matz.
New York is struggling mightily, as it sits last in the NL East with a record of 11-15.