CHICAGO -- Long before he established himself as baseball's most dominant closer, Craig Kimbrel was assigned to write about his career ambition. When he wrote about his desire to play for the Atlanta Braves, his third-grade teacher made him redo the assignment, because she did not believe he should've viewed becoming a big league ballplayer as a realistic goal.
"My mom laughs about it all of the time," Kimbrel said. "I don't know if my mom has the paper or not. But it would be pretty cool to find it to see what I said back then."
Like many other young boys who grew up in the Southeast over the past two decades, Kimbrel had visions of becoming the next Chipper Jones. But the Huntsville, Ala., native never dreamed he would actually become the man the baseball world now widely recognizes as the next Mariano Rivera.
As Rivera bids adieu to his illustrious Hall of Fame career, Kimbrel stands as the most likely candidate to spend the next decade-plus as baseball's premier closer. Through the first 228 appearances of his career, the hard-throwing Braves right-hander has notched 138 saves and surrendered just 122 hits.
The saves-to-hits ratio is just one of the many ridiculous stats Kimbrel has created during the early years of his career. His 1.40 career ERA stands as the lowest mark produced by any Major League reliever with at least 225 appearances.
"He's one of the most dominant pitchers I have ever seen," third baseman Chris Johnson said. "He's amazing. It's weird. He's like one of those guys when he gives up a hit, you're thinking, 'What happened?'"
There was certainly a feeling of disbelief last week when Kimbrel squandered a two-run ninth-inning lead against the Nationals and suffered his first blown save in more than four months while surrendering three runs in an appearance for the first time in his career. Of course, it should be noted that the only ball that left the infield during this outing was the game-ending grounder that slipped under Andrelton Simmons' glove, allowing two runs to score.
"Any time I go out there and don't do my job, it's a tough one to swallow," said Kimbrel, who enters the regular season's final week with a Major League-leading 49 saves.
Fortunately for the Braves, those instances when Kimbrel has blown a lead have been few and far between. Since becoming Atlanta's closer at the start of his rookie season in 2011, the hard-throwing reliever has notched a 90.1 save percentage. Over the past two seasons, he has blown just seven of his 98 save opportunities.
Kimbrel spent much of the 2010 season at the Minor League level and then became a key cog in the Braves' bullpen once September arrived. He proved effective enough to be used in each of the four games they played against the Giants during that year's National League Division Series.
"Getting the chance to pitch in the  playoffs and have that adrenaline and the need to learn to pitch with that kind of pressure after having completed just 20 innings in the big leagues, I think that is why I have been able to handle myself a little better," Kimbrel said.
Along with having a high-octane fastball and a knee-buckling curveball, Kimbrel possesses the stoic mindset that allows him to deal with the cruel nature of his role.
Pitching coach Roger McDowell first recognized this mindset when Kimbrel issued two walks and committed an error to load the bases with no outs in what was just his eighth career appearance, on June 20, 2010. The young reliever proceeded to strike out the next two batters -- David DeJesus and Mike Aviles -- he faced and then got Billy Butler to pop up to keep the game tied and give his teammates a chance to beat the Royals.
"Closers have a different personality," McDowell said. "It's just a different mentality that I don't think can be taught. Either you have it or you don't."
After blowing a one-run ninth-inning lead in the must-win regular-season finale against the Phillies that ended the Braves' September collapse in 2011, Kimbrel showed he has the mental resolve to handle the closer's role from a mental perspective.
All Kimbrel did was come back last year and produce one of the most dominant seasons by a Major League reliever. Along with becoming the first pitcher to strike out more than half the batters he faced (116 of 231), he converted 42 of 45 save opportunities and compiled a 1.01 ERA. The .186 on-base percentage he surrendered ranked as the third-best mark in a season by a reliever. The only two better marks were notched by Hall of Famer Dennis Eckersley in 1990 (.172) and '89 (.175).
"Looking back on some of those numbers from last year, it's still kind of hard to believe," Kimbrel said. "Luck and good timing play a part."
While Kimbrel has not been as utterly dominant as he was last year, he is approaching the postseason in the midst of an impressive stretch. Three of the five runs he has surrendered in his past 51 appearances scored during that forgettable inning against the Nationals last week.
During this 51-game stretch, Kimbrel has posted a 0.71 ERA, converted 39 of 40 save opportunities and limited opponents to a .240 on-base percentage. This impressive run began immediately after he allowed the Reds to hit back-to-back two-out homers in the ninth inning on May 7.
"What he has done is just incredible," catcher Brian McCann said. "He's doing stuff that has never been done before. He just keeps getting better."
Mark Bowman is a reporter for MLB.com.