Jerry Blevins has held left-handed hitters to a .223 average in his career. (John McDonnell/The Washington Post)

Jerry Blevins finds one personal trait of particular importance to his career and, without getting too philosophical about it, his life: honest self-evaluation. At some point this weekend, Blevins likely will jog from the left field corner of Turner Field to face two “large human beings.” The thought that crosses his mind will not burden him. It will reinforce an understanding.

“You know going in, ‘This is the reason that I’m here. These are the guys I need to get out,’ ” Blevins said. “As a grown man, you understand what your job is. I understand I have to get left-handed hitters out.”

The Washington Nationals searched this winter for a left-handed reliever, in part with the Atlanta Braves in mind. They acquired Blevins in a trade with the Oakland A’s by sacrificing sprinter-quick outfield prospect Billy Burns. The success of that deal hinges on Blevins’s ability to neutralize Freddie Freeman and Jason Heyward, Atlanta’s two best left-handed hitters.

Blevins’s encounters with Freeman and Heyward in crucial, late-game situations may determine the outcome of the three games starting Friday night in Atlanta. Any one game may determine the season series. And the season series may decide whether the Braves repeat as division champions or the Nationals take back the title.

Blevins has held left-handed batters to a .223 batting average in his career; Freeman has hit .261 against lefties, Heyward .230. Over a season that could bring a dozen matchups between them, each side will try to dial those percentages to its advantage.

“It’s a chess match, and it’s fun,” Blevins said. “That’s the part of the game that I really love. The longer guys get to know each other as hitters and pitchers, it becomes more challenging. I really thrive on that.”

From December through the spring, Blevins studied rosters to identify which batters he would face most often. He researched more lesser known lefties — Miami’s Garrett Jones, for example — than stars. “Heyward and Freeman, those guys are easy because they’re on TV a lot,” Blevins said. “You get to see them.”

Blevins looks up left-handed hitters’ performance against specific pitches from left-handed pitchers. Freeman is better than the league average against curveballs, for example, but below average against sliders.

That may have informed Blevins’s decisions already. In both his at-bats against Freeman so far, Blevins started him with a slider for a strike. In each meeting, though, Freeman overcame the hole. On Saturday, he ripped an 0-1 curveball to the gap for a double.

On Sunday, the count settled at 2-2 after Freeman chased a two-strike sinker far outside and still managed to flick it away foul. Blevins tried to make Freeman chase another slider. Freeman chased, except he still demolished it. Denard Span tracked down the line drive at the warning track in center field, sparing Blevins.

Freeman, Blevins said, “doesn’t have a singular weakness.” He marveled at how he can guard against inside pitches with arms long enough to reach — and drive — pitches off the outside corner.

“Freeman is a lot better hitter than advertised,” Blevins said. “He just signed a big deal and you hear a lot about him, but he lives up to the hype. Heyward is right on his heels. He’s a different kind of player. He relies a little bit more on speed than his power supply. But Freeman comes as advertised.”

Blevins handled Heyward on Sunday, setting him up with a curveball over the outside half of the plate, then striking him out with a slider over the middle of the plate.

The Braves bat Heyward first and Freeman third with a right-handed hitter separating them, ostensibly to punish the opposing manager for bringing in a lefty reliever to face them both. But Manager Fredi Gonzalez’s No. 2 hitter, B.J. Upton, provided little deterrent. Upton hit .184 last year, and he has started this season 5 for 33 with 14 strikeouts and no walks. On Wednesday, Gonzalez substituted Andrelton Simmons — career on-base percentage: .305 – in the second spot.

Until the Braves solve their lineup, Blevins should be able to face Heyward and Freeman with impunity. Over the course of a season, Blevins’s style should help him see the same hitters over and over.

Most relievers feature one pitch and use one other pitch to complement it. Blevins throws four pitches, giving him more patterns and sequences to choose from. Blevins throws two fastballs, one that cuts away from left-handed hitters and one that sinks toward them. He can also throw either a slider or curveball, so when a lefty identifies that the ball coming at him is about to break over the plate, he still can’t be sure whether it will loop slowly or dart away from him.

“I think having four pitches gives me the advantage long term because I can always mix it up,” Blevins said. “I’ll never have to do the same thing twice. I might. But I don’t have to, because I have the ability to work back and forth with different pitches.”

Pitching coach Steve McCatty diminished the importance of adjustments. “In this game, there are no secrets,” McCatty said. “We know their weaknesses. They know we know their weaknesses. They know what that guy is going to throw. It’s up to the pitcher to execute the pitch. It’s up to them to hit it.”

Blevins stands behind the mound before every pitch to gather himself and sort information in his head. He evaluates the last pitch and the way the hitter reacted. He considers how the count may change the plan he carried into an at-bat.

“Mostly, it’s thinking about what just happened and evaluating and not rushing, taking my time and understanding what I want to do,” Blevins said. “The number one thing you can do as a pitcher is throw whatever pitch it is with conviction.”

Conviction helped Blevins reach the majors. In the minors, he threw 97-mph fastballs past hitters. Over the 2008 and 2009 seasons, his velocity settled to its current state, around 90 mph. He learned that the way he approached hitters mattered more than sheer power. “It happened slowly,” he said, “but the realization clicked.”

It will aid Blevins every time he sees Freeman or Heyward at the plate this season. He knows why he is here.