In April, Halladay was 3-2 with a 1.95 ERA in five starts.
"I have a little ways to go mechanically and consistently but each time I feel a lot better," Halladay said.
It was the first time since coming off the disabled list on July 17 with a shoulder injury that the right-hander has looked, well, like Roy Halladay, now the owner of a 193-98 career record.
Before Saturday, Halladay was 0-1 with a 5.82 ERA in three starts since coming off the disabled list.
The only thing Halladay lost was the chance to stay in the game even longer.
"I was campaigning to keep going but I know they are trying to be cautious," he said.
More than the fact that his fastball was in the low 90s was the movement he had on his pitches, something that baffled the Diamondbacks.
"The biggest thing is the movement and being crisp with it and that has improved, especially with the cutter and sinker," Halladay said.
The worth of Halladay was demonstrated in his absence. He missed 42 games while on the disabled list and the Phillies were 15-27.
Arizona starter Joe Saunders retired the first six batters before catcher Erik Kratz led off the third inning with a line-drive home run to left, his fourth of the season. Kratz drilled a 2-0, 90-mile-per-hour fastball.
"Joe is going to come at you and is not a guy who will nitpick around and 2-0 I was able to get a ball probably more over the plate than he wanted and I was able to squeak it over the wall," Kratz said.
The playing time for Kratz should significantly increase with catcher Carlos Ruiz expected to miss between four and six weeks with a partial tear in his left foot. Ruiz, who is suffering from plantar fasciitis, was placed on the disabled list on Saturday and infielder Hector Luna was recalled from triple-A Lehigh Valley.
"The kid is strong and durable and you can work with him," manager Charlie Manuel said of Kratz. "He is hungry to play in the big leagues."
In the fourth inning, the Phillies loaded the bases on Ryan Howard's two-out single, John Mayberry Jr.'s double and a walk to Domonic Brown. Howard, following left Achilles surgery in the offseason, clogs up the base paths.
In this instance it didn't matter because Howard scored the Phillies' second run on a bases-loaded walk to Kratz.
Saunders ended the inning by striking out Nate Schierholtz.
In the sixth, Arizona's Stephen Drew hit a one-out double to left that turned Brown around. Brown banged into the wall and wasn't close to catching the ball. Drew advanced to third on a passed ball.
Halladay got out of the inning by striking out Jason Kubel and getting Paul Goldschmidt on a grounder to short.
The Phillies added a run in the eighth on Brown's two-out RBI single.
Following Halladay, the Phillies received scoreless innings from Josh Lindblom and Jonathan Papelbon, who earned his 24th save.
Contact Marc Narducci at 856-779-3225, firstname.lastname@example.org or @sjnard on Twitter.