The Padres acquired the utility infielder for a player to be named later earlier in the day, and Farrell's kind words bolstered the team's excitement about the trade.
"John had a lot of nice things to say about Pedro," Black said. "We're happy to have him here. We'll get him acclimated as quickly as possible, but he's going to be available right away."
Jaff Decker was optioned to Triple-A Tucson in a corresponding move, and third baseman James Darnell was designated for assignment to make room on the 40-man roster.
Ciriaco adds speed and defensive versatility to a team with plenty of both.
"We're excited about Pedro," Black said. "He comes in with a lot of high marks from people throughout the game. He'll be a versatile player for us. He can play every infield spot and we can move him to the outfield if we need to."
Ciriaco said he is ready for anything. The 27-year-old's whirlwind day brought him across the country in time for Friday's game against Arizona.
Ciriaco was happy with the trade, especially after being designated for assignment by the Red Sox on June 10.
"It's been a crazy day, but I'm happy to be here and I'm excited to join a team like this," Ciriaco said. "My goal right now is to introduce myself to new teammates and get on board with what they do and how they work.
"The National League game is a bit different because you have to be ready all the time. I like that. It keeps you in the game and keeps you focused at all times. I'm going to work hard and play any position they want me to."
Ciriaco has big league experience at third base, second base, shortstop and each outfield post. Ciriaco hit .216 in 28 games for the Red Sox this season and .287 in a big league career that began in 2010 with Pittsburgh.