Drabek had been struggling with his control for most of the season. He led the league in almost all of the negative pitching statistics, and seemed unable to find a groove.
Those numbers -- combined with Drabek's apparent battle with a lack of confidence -- led to the move that also resulted in right-hander Zach Stewart having his contract selected from Double-A New Hampshire.
"I think the first thing is getting back to throwing strikes," Blue Jays general manager Alex Anthopoulos said of sending Drabek down.
"Also, to be able to handle himself and relax when things get tough. It's a combination of things, but I think more importantly than anything else, if he's throwing strikes and getting ahead, he's going to do well."
Drabek wasn't doing much of that this season. He led the Major Leagues with 52 walks and was the only pitcher -- who qualified with enough innings -- to issue more base-on-balls than strikeouts.
The 23-year-old posted a league-worst 1.79 WHIP, and only Cleveland's Fausto Carmona (5.71) and Florida's Javier Vazquez (7.09) have worse ERAs than Drabek's 5.70.
Drabek also had trouble controlling his emotions when things started working against him. A bad call by an umpire, a defensive miscue, or poor location on his pitches would frequently have the native of Texas in fits on the mound.
The situation reached a breaking point following Sunday's start against Boston, when Drabek allowed a career-high eight runs. After that game he gave a very honest assessment of his recent woes.
"I'm very frustrated right now," Drabek said. "I couldn't tell you the last real quality game that I've had. It's frustrating walking people, giving up hits, not giving your team a chance to win."
Anthopoulos, along with manager John Farrell, referenced those postgame comments on multiple occasions to reporters when explaining their reasoning behind Tuesday's demotion.
"I think those comments were pretty telling that he was trying to find himself a little bit," Anthopoulos said. "It was a matter of, was he going to hope to do well or did he know he was going to do well.
"John and I talked a lot about that, and maybe from a confidence standpoint, it's to the point now, especially with those comments, maybe this is a good time to do that."
Drabek began the season with high expectations as the club's No. 3 starter. He had spent the past year as Toronto's No. 1 prospect, but he appeared ready to take the next step in his overall development.
The 2011 campaign started out well, with Drabek posting strong numbers in Spring Training and then going 3-0 with a 3.30 ERA in his first five starts of the regular season.
As the year progressed he appeared to hit a bit of a wall. Drabek's walk totals continued to pile up, and the poor results followed. In his next nine starts, he went 2-5 with a 7.38 ERA.
Drabek walked at least four batters in eight of his 14 outings this season. He walked at least three in all but one of those starts.
Despite the numbers, the Blue Jays appeared inclined to ride through Drabek's ups and downs. Farrell was adamant to reporters on Sunday that there had been absolutely no talk of a possible demotion.
But Farrell now admits Sunday's result wasn't the only reason behind the move. The whole body of work during the past two and a half months played a major role.
"It highlighted our conversation," Farrell said of Sunday's eight earned runs. "After that game we all took a night to sleep on it, to reconvene and talk about it yesterday, which we did.
"But at the same time, we've got a young pitcher going to the mound, and before the game I'm not going to say he's in jeopardy of going to Triple-A, either."
Drabek now heads to Las Vegas, where he will make his first start on Sunday. He will attempt to work his way back in the hitter-friendly Pacific Coast League, which provides notoriously tough conditions for pitchers.
The high altitude, poor fielding conditions and the presence of many advanced hitters has made the PCL an offensive-oriented league. Farrell believes that's a positive, though, and one of the main reasons the club chose Triple-A over the more pitcher-welcoming Eastern League in Double-A.
"I think the adversity that Las Vegas is going to present is what's needed," Farrell said. "It's not to try and make the environment as friendly as possible, because the environment here is not a friendly one.
"This is where the areas in need [are], to deal with these adverse conditions and where you have to repeat a consistent level of pitching. That's the difference of a guy staying here and not staying here."
Drabek's spot in Toronto's rotation will be filled by Stewart, who is scheduled to make his first start Thursday afternoon against the Orioles.
The club also considered bring up left-handers Brett Cecil or Brad Mills, but opted to take Stewart because of his recent performance. The 24-year-old is 4-3 with a 4.39 ERA in 12 starts this season, but he's 1-0 with a 2.37 ERA in his past three outings.
"Zach is someone that was very close to a callup last year," said Anthopoulos, who returned on Sunday from a trip to watch New Hampshire play. "He has done everything we asked him to do. He hasn't been up here before, his last three starts in New Hampshire he pitched well.
"Just being down there and talking to the staff they feel he deserves an opportunity. It's really a good time to give him a shot, to give him a look and see how he does."
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB b>. This story was not subject to the approval of Major League Baseball or its clubs.