One of the biggest mysteries of the past two years in the Atlanta Braves system has been the disappearance of the prospect star of Julio Teheran. Once considered among the top young pitchers in the minor leagues, he may struggle to find his way into the top-100 this year.

Braves fans were giddy about Teheran after his 2011 minor league campaign, in which he went 15-and-3 with a 2.55 ERA as a 20-year-old in triple-A. But Atlanta fans were struggling to figure out why his follow up season last year in triple-A resulted in an ERA almost twice as high (5.08), more hits, fewer strikeouts, and a lot more home runs.

One theory was that the "book" was out on Teheran, that the deception he had enjoyed while twirling through the minors was solved by Major League hitters during his cup of coffee in Atlanta in late 2011. Another theory looked at his drop in velocity, from the mid-90s to low-90s, and concluded that something might be wrong with his arm, or that he was following in the footsteps of Tommy Hanson.

In their top-10 Braves prospects Baseball America parses through these rumors with their prospect writeup of Teheran:

Teheran has an electric arm, but his delivery had some violence that the Braves wanted to iron out in order to reduce his risk of injury. In 2012, they decided to reduce the bend on his back leg during his windup. He had been turning and coiling his body to generate more momentum toward the plate, placing additional strain on his right knee and elbow. Atlanta worked with Teheran on keeping his back leg straighter in order to create a better center of balance, particularly in his core.

The Braves tweaked Teheran's delivery, something they also did with Hanson between the 2011 and 2012 seasons. BA says this led to a lot of Teheran's struggles in early 2012, including his home run binge in spring training, and his drop in velocity.

But the Braves were doing this to help Teheran in the long run -- to help reduce the risk of injury and improve his control. BA concludes:

After struggling with his confidence for most of 2012, he regained his swagger as he became more comfortable with the way he was throwing the ball.

That was the 2012 season, but not the 2012 off-season, and in a very interesting twist we get this news from the AJC, reporting on the Braves front office visit to the Dominican Winter League, where Teheran is pitching this winter:

Wren said Teheran’s motion looked more fluid. "We wanted him to get back to a more natural delivery where he’s not thinking about his mechanics, and I think he’s accomplished that," Wren said. "His mechanics were very good. He looked much more natural and like he did two years ago."

Holy 180 Batman! The Braves are almost admitting that they cost Teheran a year of development because they were tinkering with his delivery. The quote from Wren above tells me that the Braves asked Teheran to abandon the changes they made to his delivery, described in the first quote from Baseball America. I guess their intentions were right, but the results not what they had hoped for, and I suppose we have to give them credit for returning Teheran to his original delivery, from which he had the bulk of his minor league success.

That renewed "natural" delivery is leading to some impressive numbers for Teheran in the Dominican Winter League this month. In his last three starts spanning 16.2 innings, Julio has allowed only 2 hits and 4 walks while striking out 15 batters. I was able to watch an online stream of his start this past Sunday and he did indeed look like the old Julio, with a bit of a dip-and-twist in his delivery and a fastball that was consistently in the mid-90s.

Like Hanson, Teheran's high leg kick, even out of the stretch, leads to baserunners taking advantage, but it also leads to a great deal of vitally important velocity that makes him an effective pitcher. One has to wonder if we're seeing the effects of these "before and after and then before again" versions of Teheran, what might really be the problem with Hanson's loss of velocity. Are Tommy's troubles truly because of a loss of velocity, or were they because of too much tinkering with his mechanics?

I guess we'll find out the answers to all our questions this season as Teheran attempts to win a spot in the Atlanta rotation, and Hanson attempts to dispel the rumors of his demise, while pitching for the Angels.