MILWAUKEE -- Two of baseball's best young pitchers, the leading edges of two of baseball's most successfully rebuilt pitching staffs, will open this National League Division Series, Arizona vs. Milwaukee.

In a matchup fully worthy of the postseason Saturday at Miller Park, the D-backs' Ian Kennedy (21-4, 2.88 ERA) will go against the Brewers' Yovani Gallardo (17-10, 3.52) in Game 1.

The great strides these clubs made in improving their pitching from 2010 to this season have transformed them from also-rans to division champions. The D-backs are, on the surface, the most startling success story in baseball. But when you consider their pitching improvement, the success is no longer startling.

They have made the classic journey, "worst to first." Last season, they were dead last in the NL West, 65-97, the second-worst record in the league. They ranked 15th in the NL in ERA at 4.81. But this year, they ranked ninth in team ERA at 3.80. That sort of improvement, in just one season, qualifies as leaps and bounds.

The Brewers won no prizes on the mound in 2010, either. They were 77-85, a distant third in the NL Central, with a team ERA of 4.58, ranking them 14th in the NL, just one place ahead of Arizona. But this season, Milwaukee ranked seventh in the league in ERA at 3.63. Again, that kind of statistical difference from one season to the next is more transformation than improvement.

Both of these clubs have made pitching acquisitions that have been somewhere between astute and the work of genius. For Arizona, Kennedy, 26, has gone from a disappointing trial with the Yankees to a Cy Young candidacy. Daniel Hudson, formerly of the White Sox, has become a 16-game winner. Joe Saunders came with two pitching prospects in a trade with the Angels that sent Dan Haren to Anaheim. If Saunders has not had quite the season that Haren has, he has certainly been no worse than solid for the D-backs.

Kennedy traces his breakthrough success to the confidence the D-backs have demonstrated in him.

"You know, when I got announced Opening Day starter, I was really happy," he said. "That gave me the opportunity and showed that they had the confidence in me to do that and go against some of the No. 1 guys this year.

"It's been fun, a really fun year, just because I feel like as a team we've had a great, great group of guys behind me. Also in our starting rotation and pitching, everybody, all 1 through 25, was awesome to play with. Even guys we called up. We've got great guys with Aaron Hill and [John] McDonald and [Lyle] Overbay, just adding guys. We added some good, I guess good team character, and team guys."

Plus, the D-backs rebuilt their bullpen, which was a particular problem area in 2010. The primary success story here is supplied by closer J.J.Putz, who has regained the top-shelf form he had with Seattle in 2007. The D-backs signed Putz to a two-year, $10 million deal that now looks like an absolute bargain.

The Brewers did some extensive renovation on their pitching staff, as well. They traded prospects for Zack Greinke, the 2009 American League Cy Young Award winner, and Shaun Marcum, who had success with Toronto while pitching against difficult AL East opposition. Greinke got a late start due to a cracked rib suffered in a pickup basketball game, but he proved his value by going 11-0 at home. The Brewers were so enthused about his home record that they will start him in Game 2 of this Series on short rest. Marcum put together a very solid season. With emerging ace Gallardo and veteran Randy Wolf, the Brewers also have a worthy postseason rotation.

The Brewers also fortified their bullpen with the addition of Takashi Saito. After they had eighth-inning problems early in the season, they traded for Francisco Rodriguez, holder of the single-season save record. With Milwaukee, Rodriguez became the eighth-inning setup man, while closer John Axford ran off 43 straight successful save opportunities.

Gallardo, 25, started Game 1 of the 2008 NLDS against Philadelphia. The Phillies went on to win the World Series. Gallardo took the loss in that game, but over seven innings, he did not give up an earned run. On several levels, Gallardo is in a better situation as this season's Game 1 starter.

"In 2008, it was my second start coming back after knee surgery," Gallardo said on Friday. "Obviously, you know, I was very excited in 2008 and had a lot of adrenaline going on. But yet again, back of my mind, what if I have to field a bunt or something, it wasn't 100 percent.

"Now this year, I'm very excited. I'm looking forward to it. And also I was able to pitch for this team the whole year, which is also I look at it as a privilege."

And these clubs have been privileged to have the kind of pitching that makes winning divisions possible. They have made dramatic improvements in their pitching this season. These improvements have been so dramatic that they have brought these teams all the way into October, as full-fledged members of baseball's version of the Elite Eight.