Greinke, who pitched in the AL for the Royals from 2004-10, is correct in his assertion that regardless of league, the objective remains the same.
But the means by which pitchers accomplish that goal aren't always the same. There are, after all, a handful of subtle differences between pitching in the AL and NL.
The style of play, the designated hitter -- or lack there of -- the approach against the No. 8 hitter in the NL, and the reasoning behind a manager going to the bullpen, all differ from league to league.
"You're still just going out and trying to pitch," said D-backs right-hander Trevor Cahill, who was sent to the National League from Oakland during the offseason. "But there's a lot more to it in the NL in terms of small ball. There's guys trying to bunt, steal, hit-and-run more often.
"Plus you're [hitting]. At first it was pretty uncomfortable. I feel like every game I get more comfortable."
Cahill notes that pitching strategy differs between the leagues, but he's quick to point out that those differences are minor. With the lack of a DH in the NL, Cahill said sometimes he'll find himself pitching around a No. 8 hitter to get to a pitcher.
The difference in leagues traditionally impacts statistics as well. This season -- counting Greinke and Rangers righty Ryan Dempster, who was traded Tuesday by the Cubs, as National Leaguers -- NL pitchers comprise 18 of baseball's top 30 ERAs. Entering play on Thursday, the AL's 4.09 ERA was 11 points higher than the NL's 3.98 mark.
That's nothing new. There was a 0.27 point discrepancy between the leagues last year, and the average differential over the past decade is about 0.19.
"It definitely makes a difference to have a pitcher in the nine-hole," Cahill said. "But I definitely wouldn't say it's any easier [in the NL]. The American League is more of going for the big innings, but in the National League, they manufacture runs. It's tough. It's frustrating because sometimes you make pitches and all of a sudden they're doing a hit-and-run and other things you need to be aware of."
Cahill's teammate Joe Saunders went to the NL when he was traded by the Angels during the 2010 season. He said the AL-to-NL transition is much more difficult because AL pitchers headed for the NL are forced to learn the mentality of a hitter.
"I'm focused on pitching for a couple of innings, then I'm focused on hitting. That was kind of the hardest thing for me to do," Saunders said. "Now I know how to do it, but it was tough. Early on, I would miss a bunt or something and then we wouldn't score a run, and that would kind of roll over into my pitching to the next inning. That's where you have to keep flip-flopping your focus."
Saunders continually returned to the word "focus" in his analysis of pitching in an NL game. It's simple in the AL, he says. The focus is always on the next pitch, the next batter or the next inning.
In the NL, where a good bunt by a pitcher can mean the difference in a tight game, it gets tricky. Often times, too, pitchers aren't sure if they'll be returning to the mound the next inning because a manager may favor a pinch-hitter.
Since he switched leagues, Saunders said he has a new-found respect for pitchers who reach 200 innings in the NL due to the number of innings per season they lose when a manager opts to pinch-hit.
"In the American League, it's if you're doing well, you're going to be in there as long as you want," said Saunders, who tossed 212 innings in 2011. "Here, if the game's close, you never know."
There's also the issue of facing new hitters and studying new lineups upon one's arrival in a new league. But the plethora of information available today has helped even the playing field for pitchers and hitters alike when facing the unknown.
Still, that doesn't mean there aren't adjustments to be made in those areas.
"There will be a lot of unknown, learning new hitters and new teams, but with video technology the way it is, you can do a lot of homework," said Dempster, who will be pitching for an AL team for the first time in his 15-year career. "I can do it on the plane ride and in the next few days. I'll also have to lean on the pitching coach and other guys on the staff."
None of that seemed to concern Dempster too much. He quickly returned to the basic principle of pitching, which transcends the existence of the DH or league tendencies in strategy.
"If you make your pitches, you're going to get hitters out," he said.