But Happ exited his five-inning performance at ESPN's Wide World of Sports complex feeling the damage created by these adjustments that helped McCann highlight the Braves' 8-0 win with a pair of homers in his first two at-bats.
"The good thing about today is that I was working on something and I was able to take it into the game and execute it," said McCann, who added a seventh-inning single to complete a three-hit performance that raised his batting average to .483 (14-for-29).
While it has seemed like McCann has been swinging a hot bat since this month began, he obviously wasn't happy with the fact that he went hitless in two at-bats against the Mets on Tuesday and entered this game against the Phillies with three hits in the 13 at-bats he had compiled since constructing his previous two-homer performance against the Astros on March 14.
"It had everything to do with my hands," McCann said. "I went down in the cage today for a while and hit. I'm trying to keep [them] from dropping so much."
McCann realized immediate dividends when he opened the second inning with a towering homer that cleared a television truck and landed near the cars parked beyond the right-field wall. The four-time All-Star catcher then directed the first pitch he saw from Happ in the fourth over the right-center-field wall for a two-run shot.
Within a span of two pitches, McCann hit half as many homers (four) as he had hit against left-handed pitchers all of last year. In addition, he matched his career hit total against Happ, who has limited him to two hits in 12 career at-bats.
"Baseball is all about confidence," McCann said. "When you work on something and it works, you can take that into tomorrow. I've gotten into some bad habits in the last year and a half that I'm trying to break."
McCann hit .308 with 17 homers and a .932 OPS against right-handed pitchers last year. But against left-handers, he hit .225 with four homers and a .634 OPS.
Instead of blaming this on the fact that his vision problems had forced him to get used to playing with glasses, McCann recognized that the problem stemmed from the fact that his swing had gotten too long for him to consistently catch up with the pitches delivered by left-handers.
"I'm going for a shorter swing, and the quicker that I can get the barrel to the ball, the more success I'm going to have," McCann said.
With the help of Braves hitting coach Terry Pendleton and Chipper Jones, McCann has been working hard to develop a shorter swing. But until Wednesday morning, he had never truly started to feel comfortable with these adjustments.
"I've been trying to do this for a while now and I haven't been able to stick to it," McCann said. "The last couple of days, I've been getting pitches to hit and I haven't even been close. So I knew it was time to make the adjustment."
Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.