SAN FRANCISCO -- The Giants expected their starting pitching to be a strength this year, but the unit hasn’t been quite as sturdy as they imagined heading into the season.

Logan Webb, Kyle Harrison and Jordan Hicks have been constants at the top of the rotation, but the Giants have struggled to find dependability at the back end due to injuries to veterans Blake Snell (left groin strain), Alex Cobb (left hip surgery) and Robbie Ray (Tommy John surgery).

Spencer Howard is getting a chance to plug one of those holes in the interim, but the 27-year-old right-hander couldn’t get out of the third inning in his second start of the year, saddling the Giants with an 8-6 loss to the Angels in Friday night’s series opener at Oracle Park.

Howard entered Friday with a 2.03 ERA over his first three appearances for the Giants, but he couldn’t sustain that momentum after giving up four runs on seven hits over 2 1/3 innings in his shortest outing of the season.

"Just a lot of balls in play that didn’t go my way,” Howard said. “I started to try to nitpick a little too much around the zone and missed a few. I don’t think I felt what the line reflects, but certainly you learn a lot more from the ones that don’t go your way."

Down 8-1, the Giants showed late life with a five-run eighth inning that was capped by Heliot Ramos’ three-run home run off Roansy Contreras, but their comeback bid fell short after they went down in order against Angels closer Carlos Estévez in the ninth. The other offensive highlight of the night came courtesy of Wilmer Flores, who became the 17th Venezuelan-born player to reach 1,000 career hits and 150 home runs after he singled off Angels starter Tyler Anderson in the fourth.

San Francisco needed five relievers to cover 6 2/3 innings following Howard’s early exit, putting more pressure on rookie starter Keaton Winn to get back on track and eat up some innings on Saturday. Winn recorded a 3.18 ERA over his first six starts of the year, but he’s been unable to complete five innings in each of his last four, logging a 17.05 ERA over 12 2/3 innings across that span.

Getting consistent length out of the rotation has been an issue for the Giants, whose starters rank 25th in the Majors in ERA (4.55) and 28th in innings pitched (338) this year.

"We have to be better at that,” manager Bob Melvin said. “Obviously, we have some other guys coming, hopefully fairly soon, that we’ve been looking forward to getting. But yeah, it’s been a little bit of a problem."

Reinforcements can’t come soon enough for the Giants, though they might be forced to keep chasing innings until they get their first shot in the arm. The closest to returning is Snell, who is slated to throw a bullpen session at Oracle Park on Saturday. Assuming that goes well, the reigning National League Cy Young winner could progress to facing hitters in live batting practice or throwing a simulated game after that, putting him on track to potentially rejoin the rotation by the end of the month.

Cobb and Ray are looking more like second-half options, though their returns could give the Giants the type of boost they’d normally have to seek out in splashy moves at the Trade Deadline. Cobb has endured a couple of setbacks in his attempt to come back from offseason hip surgery, but he’s finally progressing and threw an encouraging bullpen earlier this week. Ray, meanwhile, already has three rehab starts under his belt and will continue ramping up in the Arizona Complex League on Tuesday.

The Giants will be relying on the trio of rehabbing veterans to emerge as key pieces in the coming weeks, not only to fortify the rotation, but also to take some of the load off Harrison and Hicks, both of whom are on pace to blow past their career high in innings this year.

“We were always going to push through where the innings limits were with these guys, regardless,” Melvin said. “How much, that was kind of what we’re trying to decide. We always felt like Cobb would be back and Robbie would be back and certainly Blake hasn’t pitched as much. At some point in time, we’ll probably be able to get some of these guys a break. But at this point in time, they feel good. We monitor them well. There was always going to be a pushing through those innings anyway. But we’ll continue to monitor them. Everybody feels pretty good physically, and we’ll see where it goes.”