Doug Fister dominated over six innings as the Nationals won for the fourth consecutive time in which he has started. (John McDonnell/The Washington Post)

The Texas Rangers might like to know what happened to those Washington Nationals they heard about before they arrived at Nationals Park. They may have expected an impotent lineup overcome by injury, so-so starting pitching, a group of dour underachievers who couldn’t catch the ball or find a clutch hit. What they got was scorching-hot bats, dominance on the mound, a brass-knuckled fist to the mouth.

Saturday afternoon, the Nationals moved back to .500 by thrashing the Rangers, 10-2, their second consecutive blowout and an emphatic departure from just two days ago, when they had lost six of seven games and their offense posted run totals in binary code — 1s and 0s. They knocked out Rangers starter Nick Tepesch after two innings, swatted a dozen hits, bashed four home runs to match their season high and won for the fourth straight start made by Doug Fister, whose presence has served as a team-wide elixir. Rather than wasting the momentum from Friday night, they added to it.

“We saw stretches of it last year where we would do this and say, ‘Okay, here we go,’ and then it would kind of die out for a little while,” first baseman Adam LaRoche said. “This was huge to build off of, to know that we can go out there and get more than five or six hits in a game and just keep pouring it on them. That’s what the really good teams do.”

Third baseman Anthony Rendon went 4 for 5, raised his average to .268, made a dazzling defensive play and laced the Nationals’ first home run into the visitors’ bullpen. Backup catcher Jose Lobaton provided the second, LaRoche made it a laugher with the third and Scott Hairston rubbed it in with the fourth. The game turned into an eight-run boat race by the sixth inning.

Before Friday night, the Nationals had scored 19 runs in seven games. They matched that total in two games against the dumbfounded and overmatched Rangers, a team that had won seven of nine.

“It’s more relaxation than anything,” Manager Matt Williams said. “They all read. They all listen. All that’s been talked about for the last week-plus, when we get in a situation and it’s not happening, everybody tries to do a little more. When you jump out early, you can relax. Once they relax, their true talents come out.”

The victory started forming Friday afternoon, when Nationals fielders gathered for their daily preparation meeting. They invited Fister. He shared how he planned to attack the Rangers, and they used his game plan to more effectively position themselves.

“They’ll do their normal meeting, but they kind of ask my opinion of how I’m going to pitch somebody,” Fister said. “What sort of things do I look at when I’m facing a guy? What are his tendencies that I’m looking at?”

The meeting lasted about 20 minutes, five minutes longer than usual because of Fister’s input. The Nationals’ starting pitcher rarely joins the defensive meeting. Coaches hope Fister’s presence will prompt other starters to attend before their starts.

“He’s leading the charge on that,” defensive coordinator Mark Weidemaier said. “He understands what he’s trying to do and how he’s trying to get hitters out. . . . He does a hell of a job — works fast, throws strikes, has a game plan, attacks hitters. It’s wonderful to watch him pitch.”

Fister allowed two runs in six innings, allowing just four hits and a walk while he struck out six. He retired the first 10 batters he faced, striking out three of them and allowing one ball out of the infield before Elvis Andrus interrupted with a double down the third base line.

Fister aimed for the quickest innings possible — beforehand, he told both Lobaton and pitching coach Steve McCatty: “We’re going out there with the mentality we’re going to not strike anybody out. We want as many groundballs as possible.”

Fister induced eight groundouts, but he also went against his plan and went for the kill with two strikes. “There’s times with a two-strike count you want to nibble,” Fister said. Five of his strikeouts came on called strikes. He froze hitters with his barreling sinker at the top of the zone, and he swung his looping change-up over the outside edge of the plate.

When the ball was put in play, the Nationals fielded flawlessly — and, in Rendon’s case, spectacularly. Do you want one reason why Ryan Zimmerman went to Potomac to play left field Saturday night? Third base may belong to Rendon for the next decade.

Put aside his whip-quick bat, though. In the second inning, Adrian Beltre crushed a low bouncer down the third base line. “That’s probably the most difficult one over there,” said Williams, a Gold Glove third baseman in his playing days. “It’s the high chopper that you can’t come get, that you have to give on.”

Rendon slid on his right knee, shot his glove into the air and stabbed the smash with a back hand. He hopped to his feet, his foot on the chalk, twisting to the right, leaving him flat-footed as he reared to throw. With no momentum, on pure arm strength, Rendon chucked the ball. LaRoche expected the throw to skip in the dirt.

“He threw a seed,” LaRoche said. “Chest-high, all the way across the diamond.”

LaRoche took one step off the base and pointed his glove at Rendon. Fister pumped his fist and smiled. Rendon craned his neck and smacked his glove.

“I don’t know, I just threw it,” Rendon said.

The Nationals began their barrage in the bottom of the second, and by the time LaRoche’s three-run homer sailed into the seats in the fourth, they had scored 17 consecutive runs in the series. The challenge will grow stiffer Sunday, when Texas hands Yu Darvish the ball.

First, Williams said, the Nationals would savor Saturday. At night, players would button up tuxedos and attend the Dream Gala, the annual charity event for the Lerner family’s foundation. In the latter innings, Williams started pulling his regulars for rest. He took out Jayson Werth, whose two-run double had stretched the lead to 5-0.

“You got to go get cleaned up,” Williams told Werth when he entered the dugout. “It’s going to take you a while.”