Matz didn't get out of the first inning of his most recent start. He allowed seven runs on eight hits in what became a 25-4 loss at Washington on Tuesday, the most lopsided defeat in Mets history.
Matz complained of tightness in his left forearm after the game. An MRI on Thursday showed mild inflammation but did not reveal any structural damage.
Matz is still listed as the starter for Sunday's game against Atlanta, but the Mets are expected to decide Friday whether to put him on the DL.
"I just think we need to see how he comes in tomorrow," manager Mickey Callaway said Thursday. "He came in today a lot better than he was before."
Even if Matz is feeling better, he still could get skipped. Matz has thrown 107 2/3 innings, 25 shy of his career high, and his workload also could be a consideration.
"He's getting up there in innings this year," Callaway said. "So we have to keep that in consideration, whether or not it's better to give him a little bit of a break."
Matz is 5-9 with a 4.35 ERA in 21 starts this season. Since the All-Star break, he has a 12.34 ERA in three starts.
If Matz does not pitch against the Braves, Corey Oswalt likely would start. Oswalt is 1-2 with a 5.27 ERA in six appearances for the Mets.