Smith is expected to be placed on the injured list with an arm injury Thursday, Ken Rosenthal of The Athletic reports.
Smith hasn't pitched since Sunday, so his likely move to the IL will presumably be backdated to July 25. Assuming that's the case, the right-hander will be eligible to return as early as Aug. 9, but his injury could lead the Mets to seek out other relievers ahead of Tuesday's trade deadline. Smith has picked up 14 holds while posting a 3.51 ERA and 1.15 WHIP in 41 innings over 37 appearances this year.