As spring training drew to a close, some Washington Nationals grew weary of the growing external expectations placed on them. Despite having never finished with a winning record, they had turned into a trendy playoff choice. Several players openly predicted October baseball, too, but not all of them: “Talk is cheap,” Jayson Werth said in late March. “We’re going to have to go out and do it.”

The talk, at least before the season’s first month has elapsed, has given way to a start even the most optimistic prognosticators could not have forecasted. As they prepare to begin a six-game West Coast swing Tuesday night in San Diego, the Nationals entered Monday night tied with the Los Angeles Dodgers, at 12-4, for the best record in the National League.

No pennants have been won in April, the month on the baseball calendar that tells more lies than any other. But the Nationals’ start has validated their hope that they are leaving a dismal past for a bright future. Through 16 games, or 10 percent of the season, they have validated the talk with success on the field.

“It gives us the confidence that we have the talent on this team to do whatever we want,” second baseman Danny Espinosa said. “We’re not even playing that well, in my eyes. Not everyone is hitting. Not everyone is clicking exactly where they want to be right now. For us to be winning ballgames against tough teams and still not have everything going 100 percent right, it’s a pretty good sign.”

The Nationals have used their hot start to prove, to both the league and themselves, that they can move from also-ran to contender. Even if they’re in first place, the Nationals’ start means little in the standings at this juncture; the last-place Philadelphia Phillies have plenty of time to make up a five-game deficit. What does it mean to the Nationals? The start reassured them and created an expectation to win.

“It’s a huge mental hurdle,” veteran Mark DeRosa said. “The guys in here, we thought we had a good team coming out of camp, ready to win. Until you do it, you don’t really, truly know. I think it validates all the talk. It is very early. But we know as a team we can win.”

The Nationals have thrived on close games, holding teams down with their dominant pitching staff and scraping out just enough runs with an offense playing without projected cleanup hitter Michael Morse, on the disabled list until midseason because of a strained right lat. The Nationals have gone 7-3 in games decided by one run or in extra innings. Already, they have won two 2-1 games, two 3-2 games and a 1-0 game.

Over a full season, one-run games typically even out for every team. The Pythagorean Winning Percentage formula, an accurate predictor of future success, gauges where a team’s record should stand based on runs scored and allowed. The Nationals have out-performed their expected record but still, at 10-6, have the third-best Pythagorean winning expectancy in the majors.

“The mettle of a team is winning close ballgames,” Manager Davey Johnson said. “As a manager, I’ve always looked at our record in close games. That talks about clutch hitting. Clutch pitching. That’s very important if you’re going to contend. You can’t get beat up in these close ballgames.”

The Nationals have won all five of their series and lost consecutive games just once. Three of their four losses either went to extra innings or were decided by one run. They can thank a remarkable pitching staff that leads the majors with a 2.34 ERA. Their starting rotation seemingly makes them immune to losing streaks. In 16 games, the Nationals’ starter has allowed one or zero earned runs 12 times.

“You may beat one of them,” Nationals reliever Ryan Mattheus said. “But good luck beating three of them.”

The Nationals’ offense has given their staff little margin for error. They have scored 3.62 runs per game, 24th in the majors out of 30 teams. They have improved their biggest offensive bugaboo from recent seasons by reaching base at a .320 clip, not exceptional but better than league average.

But without Morse, and with Ryan Zimmerman off to a slow start, they have slugged only .348 and hit 10 home runs, more than only five teams. As a result, only 11 percent of their base runners have scored, which ranks 28th.

“We understand that the pitching and the defense is a big part of this team,” Zimmerman said. “It’s amazing how that can kind of cure everything. We’re very comfortable with our team. We know that we’re going to score more runs than we have.”

The Nationals may not know if their balancing act of absurd pitching and just enough runs can last. But they now have ample evidence to believe they will remain relevant through the summer. Bad teams do not win 12 out of 16 games at any point of the season. To do it now has convinced the Nationals they can fulfill any expectations.

“In spring training we thought we could be pretty good,” first baseman Adam LaRoche said. “Everybody was talking about us being pretty good. I think we’re now slowly confirming to ourselves that we’re good. That’s when it gets really fun, when guys go from thinking something to believing it as a team.

“It’s not a fluke. Are we this good? Who knows. But we very well could be, because we’ve just done it.”