With Doug Fister and Wilson Ramos returning from injuries this week, the Post Sports Live crew debates whether the starting pitcher or catcher will have a bigger impact on the Nationals. (Post Sports Live/The Washington Post)

Last week in Houston, as Washington Nationals players poured out of the visitors’ dugout to celebrate a victory over the Astros, Gio Gonzalez and Doug Fister bolted ahead of their teammates, like two kids playing tag. Fister caught Gonzalez and wrapped him in a headlock. Gonzalez wanted to return the favor, but Fister stands 6 feet 8 inches. “I don’t think I can get up that high,” Gonzalez said.

Since the start of spring training, when he arrived as the biggest acquisition, literally and figuratively, of the Nationals’ offseason, Fister has consciously ingratiated himself with teammates. He has played cards in the clubhouse, talked strategy in the dugout, shagged flies in batting practice. But he knows the moment he will truly become part of the Nationals will come Friday night in Oakland, Calif.

Thirty-five games into the season — and three days after Robbie Ray, the pitching prospect traded to acquire Fister, earned his first win for the Detroit Tigers — Fister will make his Nationals debut. Having conquered elbow inflammation during March and rehabbed from a strained lat muscle in April, Fister will give the Nationals the rotation they imagined in the winter and will give Fister what he wanted all along.

“I’m more excited to be part of the team,” Fister said. “Yes, I’ve been here. But I’m excited to help any way that I can now, get out there and get off the mound for the first time for these guys and really feel a part of the team. It’s been a long time coming. I’m pretty amped about it.”

Without Fister, the Nationals’ starting rotation has been solid. Its 3.55 ERA ranks 10th, but 19 rotations have thrown more innings. Remove Taylor Jordan from the rotation, and the Nationals starters’ collective ERA would shrink to 3.24. With Fister throwing his cannonball sinkers, it should only improve.

Doug Fister joined the Washington Nationals this winter after a trade with the Detroit Tigers. A left-handed batter and right-handed thrower, Fister will be an asset to this season’s starting pitcher lineup. (Whitney Leaming/The Washington Post)

“We’ve all been waiting for him to come back,” reliever Tyler Clippard said. “Coming into the season, we were all excited for him to join what already was a great starting rotation. We know what kind of pitcher he is, what kind of track record he has. To know we have all the arms that we want in our starting rotation going, healthy, pitching, gives the team as a whole confidence, for sure. It’ll be a trickle-down effect throughout the whole clubhouse.”

Manager Matt Williams tempered expectations for Fister, at least at the start. First, Fister will be limited to a maximum of 100 pitches, Williams said. He compared Fister to a starter at the end of spring training, ready to compete in the majors but not at peak ability.

“I don’t think we can expect too much,” Williams said. “Doug being out that long, I don’t expect that he’s able to go out there and throw 120 pitches.”

No matter how he improves, the Nationals expect to gain intangible benefits from Fister being active “because of what he means to the team right now,” General Manager Mike Rizzo said. The Nationals expect Fister will provide stability and frequent dominance every fifth day. Between starts, Rizzo believes, Fister will improve the Nationals’ other starters. Even while on the disabled list, Fister traveled with the team the past week, constantly chatting with the Nationals’ staff.

“He’s grown on the team here,” Rizzo said. “It’s important for us to have him. You’re never as good of a leader on the DL as when you’re playing. I think he’s been a terrific leader, even being on the DL and never pitching a game for us. Another good, quality starter in the rotation is important. It’s also important to have him because of the success he’s had in the past.”

Though only 30, Fister is at least two years older than the other four members of the Nationals’ rotation. Jayson Werth and Rafael Soriano are the only Nationals other than Fister who have advanced past the divisional playoff round.

“He’s not chronologically a grizzled veteran,” Rizzo said. “He’s got a lot of experience under his belt. He’s more of a pitcher. He shows the power guys that we have the cerebral side of getting guys out. You combine the two sides, I think you got something.”

By chance, Fister will make his Nationals debut against a team from his former league. In 12 career regular season starts against the Athletics, Fister has gone 5-5 with a 3.17 ERA. Last year in the American League Division Series, he helped the Tigers come back by allowing three runs over six innings in Game 4.

“It’s exciting,” Nationals starter Stephen Strasburg said. “I know how hard he’s worked to get back here. I’m excited to be in the dugout watching.”

The Nationals have played all year without a complete team. Catcher Wilson Ramos returned Wednesday from hamate bone surgery. Now they will get back Fister, a No. 4 starter in title only, a teammate who now gets to be a pitcher.

“We’ve been waiting on that all year,” first baseman Adam LaRoche said. “I know he’s champing to get back in there. So that’ll be another big boost.”