Volquez, one of four players obtained from the Reds in the Mat Latos deal in December, impressed manager Bud Black and pitching coach Darren Balsley this spring.
"There's a lot to like," Balsley said recently of Volquez.
Volquez was 2-0 with a 3.48 ERA in five starts over 20 2/3 innings this spring. In his last start here in Arizona, Volquez allowed two earned runs in seven innings against the White Sox.
"First is his talent level," Balsley said of Volquez. "And he's perfectly healthy. There's nothing wrong with his arm. He's super-receptive to new information and is sharp.
"He knows pitching, too. I think in the past he got caught up in strictly changing speeds instead of using his fastball."
Volquez said he was surprised when manager Bud Black told him Sunday morning that he would start on Opening Day.
"Big time -- I didn't expect that when I came to Spring Training," Volquez said, smiling. "But I did everything they wanted me to, and look what I got."
Volquez might not have been the centerpiece of the December trade that saw the Padres send Latos to the Reds. That would be first baseman Yonder Alonso. Heck, Volquez might not have even been the second key piece in the deal. That was catcher Yasmani Grandal.
But Volquez might well be the most important piece for 2012, as the Padres, starving for innings eaters in the rotation, think the 28-year-old right-hander can revert back to form he had in '08, when he won 17 games for the Reds, pitched 196 innings and made the National League All-Star team.
And while Volquez still leans on the changeup, which is considered a plus pitch for him, he's embraced the Padres' philosophy of commanding the fastball down in the strike zone and on the outside corner.
"You can't deny the arm, the arm is there," Black said recently. "He just has to harness it. But the pure stuff and velocity are solid."
Following Volquez in the opening four-game series vs. the Dodgers will be Cory Luebke, Dustin Moseley and Clayton Richard.
Tim Stauffer, who started the 2011 regular-season opener for the Padres, was considered the favorite to get the nod for Opening Day again this season. But Stauffer struggled this spring, posting a 6.75 ERA. He allowed 17 runs and 35 hits in 22 2/3 innings.