Thirty minutes before acting general manager Zack Scott delivered more bad news on Carlos Carrasco’s injured right hamstring Friday, the Mets announced the addition of right-hander Nick Tropeano off waivers from the Giants.

The timing of the addition seemed fitting, since Carrasco getting shut down made it necessary for the first-place Mets to add someone capable of starting. Carrasco got a platelet-rich plasma injection Wednesday, which the team hopes will help him strengthen the torn hamstring that has sidelined him all season, Scott said.

Carrasco now is not expected back until late July, and Noah Syndergaard is still a few weeks away from picking up a baseball again after an MRI exam revealed right elbow inflammation during his road back from Tommy John Surgery.

“Obviously with some of the injuries we’ve had to guys like Noah and Carlos, they’re being out a little longer than we hoped initially, we wanted to make sure we had enough to cover us,” Scott said before the Mets’ 3-2 win over the Padres at Citi Field.

There are certain markers that Carrasco wasn’t able to reach before he could ramp up his activity, which is why they opted for the shot. In early May, Carrasco was believed to be close to starting a rehab assignment, but his hamstring was still not feeling right, The Post’s Mike Puma reported at the time.

“We hit kind of a plateau in terms of strength gains,” said Scott, who believes a late July return remains possible for Carrasco.

Without Carrasco and Syndergaard, the bottom of the Mets’ rotation has struggled to match the excellence of top-three pitchers Jacob deGrom, Marcus Stroman and Taijuan Walker.

Joey Lucchesi started poorly before pitching well in his past three starts, though he has yet to get past the fifth inning in any of his outings. After a strong debut last summer, David Peterson has given the Mets few innings and poor results for the most part this year. His ERA shot up to 6.32 after he allowed four runs on eight hits over 2 ²/₃ innings in a loss to the Orioles on Tuesday. In his prior outing, he flushed a four-run, first-inning lead and recorded just one out against the Diamondbacks.

“I have confidence in him,” Scott said. “Obviously, we’re fairly thin in general. It’s not like we have slam dunk options, guys coming off the IL that will push him out. I still think he’s someone that can help us. I have that confidence.”

It doesn’t help that depth starter Jordan Yamamoto is currently on the 60-day IL with shoulder discomfort and prospect Thomas Szapucki has battled consistency issues at Triple A. That’s part of why the Mets added Tropeano.

The 30-year-old Long Island native was 1-0 with a 1.50 ERA out of the bullpen for the Giants this year before getting designated for assignment. He has made 39 starts among his 53 appearances across seven big league seasons.

The Mets, after all, will need extra starters this month due to three scheduled doubleheaders and just one off day. With the status of Syndergaard and Carrasco so uncertain — team president Sandy Alderson said Thursday on MLB Network that Syndergaard’s new projected return date is the start of September — starting pitching could be their top priority at the trade deadline, too.

“Having those two guys, one maybe ready before the deadline, one won’t be ready before the deadline, obviously that’s going to influence what we’re looking at right now,” Scott said. “Starting pitching depth is always something I feel like every deadline of my career we’ve been looking for that. So yeah, that definitely contributes to how we’re thinking about it.

“The more you can add, the better.”