WASHINGTON -- With their catching depth stretched to the limits, the Mets received a significant boost on Saturday when they activated starting backstop James McCann from the injured list. He served as New York’s 29th man for their doubleheader against the Nationals, so no corresponding move was necessary.

McCann had been sidelined since Aug. 16 with a bout of back spasms that team officials initially did not consider serious enough even to warrant an IL stint. But the tightness in McCann’s back lingered to such an extent that he was unable to run full speed until this week. Even now, the Mets plan to remain cautious with McCann, who may not immediately be able to assume a full starter’s workload.

“We’ll see day to day how he responds,” manager Luis Rojas said.

Complicating matters is the fact that third catcher Chance Sisco was still being evaluated Saturday morning from the collision he endured the previous night at home plate during the Mets' 6-2, 10-inning victory over Washington. Although concussion tests came back negative, as did testing on Sisco’s left knee, he could remain unavailable for a bit. The Mets started Patrick Mazeika in Game 1 of Saturday's doubleheader, with plans to use McCann in Game 2.

If Sisco is healthy enough to avoid the injured list, the Mets will consider keeping him on their active roster even beyond this weekend to give them protection against anything happening to McCann. Their usual backup catcher, Tomás Nido, isn’t eligible to come off the IL from a sprained left thumb until Tuesday and is not guaranteed to return at that time.

It is a complicated problem that McCann can ease significantly if he’s able to stay healthy. Before going on the IL, McCann was batting .240/.303/.357 with nine home runs in 99 games during the first season of a four-year, $40.6 million contract.