Arizona delivering in the West

Updated: May 27, 2011, 1:13 PM ET
By Buster Olney

The Rockies lost their best pitcher this week, in Jorge De La Rosa, and then the Giants lost catcher Buster Posey. Meanwhile, the Diamondbacks keep winning, keep gaining momentum.

With their victory on Thursday night, they are within 1½ games of the first place Giants, and keep in mind, Arizona has done this while grinding through the worst schedule in the National League in the first quarter of the season; 27 of its first 37 games were against teams that had records over .500 last year.

And Arizona keeps getting better, as the Diamondbacks tinker with their roster. The bullpen ERA is about half of what it was last year, and the rotation has stabilized, with Ian Kennedy and Daniel Hudson. And there is Josh Collmenter, who has a 1.19 ERA in part because he throws the ball like nobody else in the majors.