Stephen Strasburg — sporting the No. 42 in honor of Jackie Robinson day — is rocked for six earned runs in four innings. Strasburg now has an 8.61 ERA over four starts at Marlins Park. (Mike Ehrmann/Getty Images)

Tuesday was a day the Washington Nationals hope to forget soon. Stephen Strasburg started but too often found the heart of the plate and the Miami Marlins’ bats. He put the Nationals in an early deficit that mounted dramatically in the middle of the game under reliever Craig Stammen. The Nationals added two errors to their growing total. The starting lineup was utterly dormant and produced one hit through the first seven innings one night after a thunderous performance.

And by the fourth inning of the 11-2 blowout loss, the benches cleared after Ian Desmond and Marlins catcher Jarrod Saltalamacchia jawed at each other when starter Tom Koehler fired a wild fastball too high and too close to the Nationals shortstop. In Game 14, the Nationals suffered their most lopsided loss of the season, and it was against an opponent they should be battering. In fact, since the start of the 2013 season, the Nationals are 18-6 against the Marlins, which makes Tuesday’s beatdown more unsettling.

The Marlins also entered with an eight-game losing streak.

“It’s important that we play well,” Manager Matt Williams said. “Still didn’t play well [Tuesday night]. So that’s troubling. Troubling with kicking the ball around again.”

Good teams hoping to win a division shouldn’t lose games by such a wide margin. And if they do, they wash them away as quickly as possible. But there are small trends to keep an eye on two weeks into the season.

The Nationals are hitting well—for now. When will the dreadful fielding and injury woes catch up? The Post’s Adam Kilgore discusses the early highs and lows for the team. (Post Sports Live/The Washington Post)

Despite a focus in spring training on defense, the team has committed 15 errors in 14 games. The starting rotation, the supposed backbone of the team, has a 5.06 ERA, which would rank fifth worst in the majors.

They have looked strong at times and then difficult to watch other times.

“It’s important for us to be able to pitch the first inning and be ready to compete in the first inning,” Williams said. “The struggles with the starters have been early.”

For seven innings Tuesday night, the Nationals’ only hit was Anthony Rendon’s single to right field to begin the game.

Koehler, Miami’s fifth starter, was wild at times and walked five batters. But the Nationals converted none into runs.

The Nationals finally added another hit with two outs in the eighth inning off reliever Dan Jennings with Bryce Harper’s single — and then a run after rookie Steven Souza Jr.’s first major league hit. Another rookie, Zach Walters, entered as a late-game substitute and drilled his first major league home run in the ninth inning.

The Nationals, on the other hand, were done in by their pitching. Strasburg’s command was off from the start, and the Marlins pounced on him.

He allowed a leadoff single to Christian Yelich to begin his outing. Then he allowed a single to Marcell Ozuna. Then he served up a booming three-run shot to center, a blast of more than 420 feet, to slugger Giancarlo Stanton. Since the start of the 2010 season, Stanton has 20 homers against the Nationals, nine more than the next-highest total.

“I think for me if I can get through the first couple innings unscathed, I’m pretty much able to shut the door from there,” Strasburg said. “The biggest thing is that pitch to Stanton. I’ve got to do a better job of executing that pitch. I can live with a couple runs here or there in the first, but that put me behind the eight ball.”

Stanton’s influence over Nationals pitching continued in the second inning when, after a Strasburg wild pitch allowed two runners to move into scoring position, Williams elected to intentionally walk the slugger to load the bases instead of facing him with one out. The tactic worked initially when Garrett Jones hit a groundball to Adam LaRoche, who fired home for a force out. But the next batter, Casey McGehee, singled to left field and drove in two runs.

Five outs into the game, the Nationals trailed 6-0.

Strasburg’s command was off, and the Marlins took advantage. Four of the six hits he allowed in his four innings were on the first pitch of the at-bat.

“I’ve just got to do a better job of not worrying about that and keep pounding the strike zone,” he said.

The deficit turned ugly when Stammen entered in the fifth inning for Strasburg and surrendered five runs on six hits and a walk to make the score 11-0.

His throwing error to third to try and cut down a base runner allowed two runs to score. Tyler Clippard, a valuable reliever, and Rafael Soriano, the closer, pitched the seventh and eighth innings of a lost game.

The game’s biggest fireworks occurred in the fourth inning. With the Marlins leading 6-0, Koehler’s second pitch to Desmond ran high and inside. Saltalamacchia, however, had set up outside. After the game, Koehler said he was trying to throw pitches to both sides of the plate.

Desmond didn’t like the pitch running inside to him and didn’t take it lightly. He said something to the effect of “Throw the ball over the plate.” Two batters earlier, Koehler threw a fastball high and inside to Jayson Werth, who drew a six-pitch walk.

Desmond said he didn’t intend for the situation to escalate but admits he was caught up in the heat of the moment. Nor did he think Koehler was trying to hit him.

“This is how I feed my family,” he said. “I’m not scared to get hit. I’ve been hit plenty of times and never said a word. Up around the hands and head, I just don’t like that.”

As Desmond adjusted his batting gloves after making his remark, Saltalamacchia talked back to Desmond. “ ‘Hey, man, we weren’t trying to hit you, relax,’ ” he said he told Desmond. The exchange became heated, and home plate umpire Marty Foster stepped between them. Saltalamacchia removed his helmet, and then both benches and bullpens emptied. An umpire pushed a heated Koehler away from the mass of bodies.

“Little surprised, I guess,” Saltalamacchia said of Desmond’s reaction. “Not sure what the issue was. Maybe he was frustrated or something. We were trying to pitch our game.”

Umpires warned both benches. After a few minutes, players returned to their places peacefully and play resumed. And when it did, the Nationals turned in an ugly performance they hope to wash away quickly.