Randy Johnson struck out 16 Chicago batters Sunday afternoon. (Matt York/AP)

This wasn't even a vintage Big Unit effort. It was better. Especially when it comes to sheer, unadulterated power pitching.

"This might have surpassed some of the others, and that's hard to do," said manager Bob Brenly, who's seen Johnson pitch for the past four seasons. "Velocity alone, this was by far his best game of the season."

Do tell. The speedgun clocked Johnson's strikeout pitch of Mark Bellhorn in the seventh inning at 102 miles per hour, the loud popping sound of the ball hitting catcher Chad Moeller's glove echoing like a sonic boom.

Johnson, unraveling that huge, elongated body then uncoiling that whiplike left arm with the rapidity of a, well, rattlesnake, hit 100 mph even twice, 99 twice and 98 mph an incredible seven times as he struck out 16 batters.

"He very obviously was in a nice rhythm," said Brenly, who marveled as the 6-foot-10 Johnson won his sixth straight game and lowered his ERA to a Major League-leading 2.44. "With his mechanics being free and easy, the ball was just jumping out of his hand today and the radar was lighting up the board.

"That," added Brenly, "was as good as I've seen him."

Johnson, who turns 39 on Sept. 10, is in a hot race with teammate Curt Schilling (21-4) for the Cy Young Award, and has amazing numbers. He has 3,691 career strikeouts, good for fourth place on the all-time list and is 10 Ks behind Bert Blyleven (3,701). Johnson is 11-0 with a 2.13 ERA in 12 career starts against the Cubs, but merely shook his head when asked why.

It was probably a silly question, anyway, as Johnson has dominated most clubs, especially during this sensational stretch, going 10-2 with three no-decisions since June 15.

The Big Unit had a simple, humorous reply when someone also asked why he pitched such a powerful game Sunday.

"I just woke up today and I was a power pitcher," he cracked.

Still, it was hardly a perfect game, and the Cubs had their chances, loading the bases with two outs in the fourth, and putting two other runners on with no outs in the sixth. But Johnson shut down the threats to earn his 33rd career shutout.

Now in his 14th season, Johnson took a playful poke at himself after singling in two runs in the five-run eighth inning, scoring Erubiel Durazo and Matt Williams. What a pitcher, what a hitter.

"(Cubs starter Juan) Cruz was throwing hard; I was just hoping he didn't hit me," said Johnson, who admitted his velocity was quite unexpected this game but has been there in various degrees for him nearly all year, especially over the past few weeks.

"You just stay positive and stay focused," said Johnson of his consistency. "You work hard, and I'm looking forward to Friday (Aug. 30) to pitch (against San Francisco at Bank One Ballpark)."

Brenly, meantime, was determined to stay unbiased on who he thought would eventually win the Cy Young Award, something Johnson has accomplished four times, including each of the past three seasons. Schilling has never won the coveted trophy for pitching excellence.

"They're both having a heckuva year, but I don't have a vote -- it doesn't matter what I think," laughed Brenly. "One's a righty, one's a lefty. They both get people out, they both win games and they're both very competitive, but I'm not even going to start comparing those two. I love 'em both the way they are."

The Diamondbacks now venture into Dodger Stadium for a three-game series starting Monday night. Schilling will be eyeing his 22nd victory, opposing Omar Daal (10-6).

Rich Draper covers the Diamondbacks for MLB.com. He can be reached at mlbrdraper@aol.com. This story was not subject to the approval of Major League Baseball or its clubs.