General manager Kevin Towers said it was a "tremendous" addition for a team that's coming off a 99-loss season and will have several inexperienced players, including Hundley.
"We wanted somebody who not only would have a strong clubhouse presence but somebody who's caught some of the elite pitchers in the game and also somebody who can help a guy like Nick Hundley hopefully grow into one of the elite everyday catchers in the game," Towers said.
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On Tuesday, Towers called the recently retired Maddux, who was teammates with Blanco with the Chicago Cubs and Atlanta Braves.
"When you get strong endorsements from guys like Greg Maddux, it opens up your eyes," Towers said.
Maddux pitched for the Padres from 2007 until being traded to the Los Angeles Dodgers in mid-August last year.
Blanco was credited with helping mentor Cubs catcher Geovany Soto, who won the NL Rookie of the Year award last season and was the first rookie catcher to start for the NL in an All-Star game.
The Cubs declined Blanco's $3 million option in October.
A backup most of his career, the 37-year-old Blanco hit .292 with three home runs and 12 RBIs in 58 games last season. He said he enjoys helping younger catchers like Hundley.
"I'm going to be there for him like I did with Geovany Soto," Blanco said from Venezuela on a conference call. "I like the situation. I like to help as much as I can and try to make sure the guy turns out to be one of the best."
Hundley, 25, was promoted from Triple-A Portland in early July after Michael Barrett fouled a ball off his face and was lost for the season. Hundley started 55 games.
Both Barrett and Josh Bard, who also missed significant time with injuries, cleared outright waivers and chose to become free agents. Bard signed a non-guaranteed, one-year contract with Boston, and Barrett signed a minor league deal with Toronto.
Blanco has played parts of 11 big league seasons with the Dodgers, Colorado Rockies, Milwaukee Brewers, Braves, Minnesota Twins and Cubs. With Blanco's knowledge of NL hitters, Towers said it's almost like having an advance scout.
"With Nick never catching a full year in the big leagues and certainly the stress levels that come along with catching in the big leagues, still learning the National League, that's one of the things that's important with having somebody like Henry," Towers said.