Ross, whose younger brother Joe is also in the Padres organization, was in the process of transitioning from starter to reliever with the A's. He endured a rough season spanning five stints in Oakland this year, going 2-11 with a 6.50 ERA and .327 opponents' average in 18 games (13 starts).
The hard-throwing Ross, equipped with an exceptional slider, found greater success at the Triple-A level, compiling a 6-2 record and 2.99 ERA in 15 games -- 13 starts -- with Sacramento.
In Kirby-Jones, the Padres get a first baseman who racked up a .382 on-base percentage and slugged .461 in 115 games at Class A Stockton this year. The 24-year-old right-hander hit .248 with 21 home runs and 69 RBIs.
By giving up this power prospect, the A's reeled in a potential option at shortstop, their biggest need of the offseason, in the versatile Parrino, who hit .207 with one homer and six RBIs in 55 games with San Diego. He appeared in 26 games at shortstop and 15 at second base, while also playing two games at third and one in right field.
The 27-year-old switch-hitter spent the balance of the season with Triple-A Tucson, batting .328 with one home run and 32 RBIs in 65 games, spending the majority of his time at shortstop.
Werner, meanwhile, got a taste of the Majors following his Aug. 22 callup from Triple-A Tuscon, going 2-3 with a 5.58 ERA in eight starts with the Padres. The 25-year-old southpaw was also 5-10 with a 3.70 ERA and a .271 opponents' average in 22 Minor league starts, four with Tuscon and 18 at Double-A San Antonio.