Antonelli and a fellow rookie, left-handed pitcher Wade LeBlanc, joined the Padres' youth movement -- already in full swing -- on Monday, when they had their contracts purchased from Triple-A Portland.
Antonelli and LeBlanc stepped inside a clubhouse on Monday that probably looked a lot like their one in Portland, joining a roster that is peppered with players who have played with the Beavers at some point this season.
And there's more to come, as the Padres will use the final month of the season as a way to gauge what exactly they have -- or don't have -- with an eye on building for 2009.
"We just felt this was the appropriate time," general manager Kevin Towers said. "We're pretty much out of the playoff race and we saw them both on our ballclub next year. Why not bring them up in September to get their feet wet?"
The Padres will add two more players Tuesday, likely catcher Luke Carlin and outfielder Chip Ambres. Towers said two additional players will follow from Double-A San Antonio, possibly outfielder Drew Macias and first baseman Kyle Blanks.
Antonelli made his Major League debut Monday, facing future Hall of Famer and former Padre Greg Maddux. He singled in his first at-bat and figures to get the majority of the playing time at second base after the release of Tadahito Iguchi on Monday.
Antonelli hit .215 this season with Portland, with seven home runs and 39 RBIs, though he finished strong, hitting .290 in August, with four home runs. Antonelli had 76 walks with Portland and felt like, at times, he was the victim of bad luck offensively.
"It was really frustrating," Antonelli said. "I think my walks and strikeouts were the same as they usually are. The hits weren't coming. I knew there was something wrong. When I would square up a ball, I was fouling balls back or getting jammed.
"Now I'm back to swinging the bat the way I was supposed to. I finished strong, and that's all I wanted to do. I will just come up here and do my best."
Towers said he wouldn't be surprised to see Antonelli, who had a track record of being an on-base machine in the Minor Leagues, to have more success with San Diego than he did in Portland.
"I think being able to advance to this level will take some pressure off him," Towers said. "Sometimes the toughest step is getting there. I wouldn't be surprised if he performs better at this level."
LeBlanc finished fast as well, allowing one run or less in six of his final eight starts. He finished the season 11-9, with a 5.32 ERA and a keen sense of appreciation for what he went through in April (9.27 ERA) and May (6.56).
"If you look at it as a failure, you won't make it through the season," LeBlanc said. "I looked at it as if that struggle will help me in the long run. In the second half, I just got more comfortable with my stuff and my mechanics. I gained a lot of confidence in my two-seam fastball and had some good results."
LeBlanc will make his Major League debut on Wednesday against the Dodgers.