SAN FRANCISCO -- Bob Melvin spent the past two seasons managing Blake Snell in San Diego, but even he wasn't entirely sure what to expect from the reigning National League Cy Young winner in his Giants debut on Monday night.

Signed to a two-year, $62 million deal on March 19, Snell didn't have enough time to appear in a Cactus League game before the Giants broke camp, forcing him to get his work in on the Minor League side. The 31-year-old left-hander got one final tuneup against his Giants teammates in a simulated game at Dodger Stadium last week, but Monday marked his first true taste of game action this year.

"It was an unorthodox spring for him, trying to ramp up," Melvin said. "He hasn't really pitched in a game game. Some unknowns going out there."

Snell wasn't at his sharpest in his first appearance in a Giants uniform, giving up three runs on three hits over three innings in the club's 8-1 series-opening loss to the Nationals at Oracle Park.

"There’s a lot going through my head right now, but I’ll just say I was pretty amped up and I was trying to nitpick the zone too much," Snell said. “I made the bullpen have to cover a lot of innings that they shouldn’t have had to cover.”

Snell got up to five innings in his last simulated outing, but the Nationals managed to run his pitch count up to 72 pitches and force him out of the game early. Despite the short start, Snell still flashed his electric arsenal, topping out at 97.1 mph with his fastball while striking out five and walking two.

“They made him throw a lot of pitches,” Melvin said. “Seventy-five was about what we were looking to get out of him today. At least he’s off and running. Not a great game for us all the way around. But we knew it would probably be a shorter outing for him today.”

Giants fans got the whole Snell experience, beginning with the game's first batter. Snell fell behind, 3-0, before getting Jacob Young to chase a low changeup for his first strikeout of the night. Lane Thomas reached on a two-out single after lining a full-count changeup past a diving Matt Chapman at third, but Snell left him stranded by striking out Joey Gallo, swinging on a 96.1 mph fastball to end the inning.

The Nationals clipped Snell for three runs in the second. After issuing back-to-back walks to put a pair of runners on with one out, Snell surrendered an RBI single to Trey Lipscomb to put the Giants in a 1-0 hole.

Luis Garcia Jr. brought home another run by beating out an infield single to the right side, and the Nationals added on after Garcia and Lipscomb executed a successful double steal. Snell appeared to have Garcia picked off after he took off for second, but the Giants couldn't run him down before Lipscomb raced home from third and slid in ahead of Snell’s throw to catcher Patrick Bailey.

“You don’t want to have to get it in the pitcher’s hands, especially a left-handed pitcher that has to pivot and throw back the other way,” Melvin said. “You’d like to see it done in a throw or two.”

Snell returned to the mound in the third with his pitch count at 59, but he needed only 13 pitches to retire Thomas, Gallo and Joey Meneses in order. He was replaced by left-hander Erik Miller in the fourth and departed with the Giants trailing, 3-1.

San Francisco’s bullpen couldn’t keep it close after that, with rookie relievers Miller, Landen Roupp and Kai-Wei Teng combining to give up seven runs over 5 1/3 innings.

It proved too big of a deficit for the Giants’ slumping bats to overcome. Jung Hoo Lee led off the bottom of the first with a single and scored from first on LaMonte Wade Jr.’s double to left field, but the Giants were blanked the rest of the way.

San Francisco finished 0-for-10 with runners in scoring position and has plated only seven runs over its last four games, dropping to 4-7 on the season.

While he still has some rust to knock off, Snell said he’s looking forward to building on Monday’s outing and strengthening as he re-acclimates to big league competition.

“I’m excited about where I’m at, how the ball is coming out,” Snell said. “I’m only going to get better. It’s going to get more crisp. First game, I’m happy it’s out of the way. A lot to learn from it. Really looking forward to what I’ll be able to do Sunday against Tampa.”