When McGowan struggles with trusting completely in his impressive pitch arsenal, he experiences meltdowns similar to the one he had on Saturday night. McGowan decided to abandon his faulty curveball at Fenway Park, and the Red Sox exploited the pitcher's more predictable approach and sent the Blue Jays to a 9-4 loss.
"Now that I look back, I should've thrown a couple more just to show I had it," said McGowan, second-guessing his decision after giving up a career-high three home runs. "Maybe I could've gotten a feel for it."
Manager John Gibbons shared that sentiment after the defeat, which dropped the Jays (44-46) 11 games behind Boston (55-35) in the American League East. Gibbons was upset that McGowan threw his breaking pitch out of the equation, which downgraded the 25-year-old starter's repertoire to a fastball, changeup and an inconsistent slider.
"He really never could get anything established," Gibbons said. "I didn't think he did a very good job of using all his pitches. By that I mean breaking balls, which is a big pitch for him. He was pretty much limited to fastball and changeup."
The curve has been an important factor behind the success McGowan has experienced since moving into Toronto's rotation at the beginning of May. When the right-hander has a good feel for the sharp pitch, it helps offset his overpowering fastball and keeps opposing batters guessing -- much as they did during McGowan's complete-game one-hitter on June 24.
McGowan practiced snapping his curve in the bullpen before taking the mound against Boston, but he wasn't satisfied with how the pitch was working. He attempted to use the breaking ball again over the first few few innings, but found that the pitch was sailing outside the strike zone.
"I tried to get on the mound and throw a couple, but it just wasn't there," he said. "It was one of those things that just went away."
That didn't stop catcher Gregg Zaun from calling for curveballs as the game wore on. Even after McGowan decided against using it, Zaun tried to convince the pitcher to give it another shot. Instead, McGowan opted against going with the veteran catcher's signals.
"He threw it down," said McGowan, referring to Zaun's signs. "I was the one who shook it off. In my mind, I was thinking I didn't want to put myself further behind in the counts with it."
The absence of a strong curveball helped the Red Sox pounce on McGowan, who exited after giving up eight hits in five-plus frames. In the first inning, the right-hander fell into a 3-0 hole against Boston slugger David Ortiz, who then drilled a fastball over the short wall in right for a solo shot -- his first homer at Fenway since April 21.
"That's a tough situation," McGowan said. "You know in the back of your mind it's 3-0 and there's a good possibility he might swing. Then again, you don't want to four-pitch-walk him right there in the first inning. It was one of those situations where you had to throw it and throw a strike. He hit it."
Ortiz wasn't the only left-handed batter to take advantage of McGowan's limited approach. Coco Crisp, Eric Hinske and Jason Varitek combined with Ortiz to go 5-for-10 with one double, one triple and three home runs, driving in six runs off McGowan.
Entering the game, McGowan had limited lefties to a .254 batting average. He had also given up just two homers in his previous 10 starts, and only four this season. All seven of the moon shots McGowan has given up this year have been against left-handers, though.
"Those lefties on that team can really hit," he said. "They have a lot of power on that team, and they get paid to hit mistakes. Tonight they hit them."
Varitek's two-run blast in the sixth inning, which landed deep beyond the center-field wall and subsequently ended McGowan's evening, kicked off a five-run frame for Boston. It also effectively erased the work that Toronto's offense did against Red Sox starter Daisuke Matsuzaka.
The Blue Jays managed four runs -- three on homers of their own -- over six innings against the right-hander. Troy Glaus and Aaron Hill, who each finished a triple short of the cycle, both belted home runs off Matsuzaka, who gave up nine hits in the outing. Hill's blast knotted the score at 4 before McGowan's final mistake sent the Fenway faithful home happy.
As far as Gibbons was concerned, though, the night unraveled when McGowan stopped trusting in his curve.
"It's really something he's got to stay with," Gibbons said. "Eventually, usually, it clicks."
Jordan Bastian is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.