LAKE BUENA VISTA, Fla. -- It is remarkable how much Julio Teheran has changed since he briefly introduced himself to the Major League scene as a wide-eyed, 20-year-old heralded prospect who was admittedly intimidated as he made his Atlanta debut in front of a raucous sold-out crowd in Philadelphia on May 7, 2011.
During the nearly three full years that have since passed, Teheran has benefited from the natural physical maturity and mental toughness that he gained as he lost his prospect status in the midst of a trying 2012 season he spent with Triple-A Gwinnett.
But many of those who began to cast doubt on his future potential quickly became believers again as Teheran went 14-8 with a 3.20 ERA in the 30 starts he made as a rookie last year. Along with producing impressive statistics, the young hurler also displayed a mature approach that gives the Braves confidence he is capable of dealing with the pressure of making his first career Opening Day start on Monday in Milwaukee.
"He's got some old-school pitcher in him," catcher Gerald Laird said. "He's not out there to hurt anybody. But he knows on that day, it's his day to pitch and that's his plate. He wants to win, and he's out there to beat you. You can see when guys get a hit or hit a home run off him, he gets upset. It's fun to go out there and compete with him."
On the way to ranking second in the National League last year with 13 hit batsmen, Teheran did not assume the appearance of a headhunter. But his willingness to pitch inside certainly caught the attention of opposing hitters who saw the young hurler's confidence grow with each passing month.
If there were any lingering questions about the attitude Teheran brings to the mound, they were seemingly answered on Aug. 6, when Teheran did not appreciate how Nationals outfielder Bryce Harper reacted after hitting a home run in the third inning. Two innings later, Harper was drilled on the right hip by a fastball that seemed to find its mark.
Instead of reacting in an insincere apologetic manner, Teheran simply walked directly toward the first-base line as Harper yelled in his direction. Once the benches-clearing standoff ended without anything more than words being exchanged, the Braves saw their young right-hander complete his victorious six-inning effort in an unfazed manner.
"His mentality is he doesn't care who you are," first baseman Freddie Freeman said. "If you're taking some good swings against him, he's going to come after you. I don't think that is around the game anymore. If somebody is taking good hacks at you, they would have hit you right away 10-15 years ago. He has that mentality of 10-15 years ago. I think that is going to make him special for a lot of years."
In the process of posting a 1.80 ERA in the six Grapefruit League starts he made this year, Teheran once again caught the attention of his teammates after he nearly hit Miguel Cabrera in the head with a wayward fastball. Instead of allowing himself to be unnerved, Teheran remained focused and ended up using his oft-filthy slider to strike out the Tigers' slugger.
"That just shows you how good of stuff he has," Laird said. "He can lock it in with men on base. What he did to Cabrera that at-bat, his slider can be devastating when it's on. You can tell when guys get on base, there's that little light that flips in his head, and he becomes even more nastier.
"He's got a good edge to him. He's got edge out there. He's not OK with giving up hits and runs. He's a competitor. He wants to win and he wants to be great."
After allowing at least four earned runs in each of his first three starts last year, Teheran sat inside the visitors' clubhouse at PNC Park and intently listened to the direction being provided by Braves pitching coach Roger McDowell and bullpen coach Eddie Perez.
Six days later, while pitching in frigid temperatures at Coors Field, Teheran limited the Rockies to one run over seven innings. This marked the beginning of a torrid stretch during which he posted a 2.81 ERA in his final 27 regular season starts.
"I've seen him grow from when he came to [big league Spring Training] for the first time," McDowell said. "Where he is now, he's obviously got a different look. As we saw last year, he has that feeling like he belongs, and he's not as unsure of himself."
Teheran was humbled last year when he allowed six earned runs and exited during the third inning of Game 3 of the NL Division Series against the Dodgers. But while that outing might have had a lingering adverse effect a few years ago, Teheran now has the confidence that it was just one of those experiences that will prove beneficial as he approaches what appears to be a bright future.
"I would say getting the experience is the biggest thing that happened last year," Teheran said. "I was just trying to keep that mindset that I'm the best out there."
Mark Bowman is a reporter for MLB.com.