According to Padres manager Andy Green, the 32-year-old Richard can add depth and be used in a variety of different roles, whereas Thornton was more of a one-inning arm.
"Clayton Richard has the possibility of starting, he can go long, he can come out of the 'pen," Green said. "At any point in time he can be up to five or six innings. If [we need a] spot start, he can do that for you.
"So he kind of fills a need that's a little bit different than a need Matt could fill."
Richard pitched for the Padres from 2009 to 2013. He threw 14 innings for the Cubs this season in nine relief appearances, posting a 6.43 ERA, but will likely have the opportunity to start in San Diego. This factor, in addition to his familiarity with pitching coach Darren Balsley and Green (who managed him in Double-A with the D-backs organization), led him to sign with the Padres.
"In baseball that's all you can ask for, the opportunity," Richard said. "And then you try to make the most of it. So I've been preparing for a starter's role, knowing that I'll be in the bullpen and, hopefully, having the opportunity to start down the road.
"You never know how that works out in baseball, but I'll be prepared for whatever comes my way."
Green called Richard "one of the best people I've ever been around," and was looking forward to his presence around the many young pitchers on the Padres' active roster, in addition to the versatility he offered on the field.
"He's a really positive influence, and I think probably at some point in time you'll see him on the mound in a starting capacity too, because he's got that in his arsenal," Green said. "We're exited to have kind of the guy that can do absolutely everything for us."
Richard last started a game for the Cubs on Aug. 2, 2015, but with players like Paul Clemens, Christian Friedrich and Luis Perdomo in the starting rotation, it's likely he gets another start at some point this season.
Green said that with Friedrich, in particular, the team was going to be cautious. The 29-year-old threw just 58 1/3 innings last season as a reliever, and is up to 81 1/3 this year. While there's no hard limit on Friedrich's innings at this point, Green said, "Pushing him much past 120 [innings] is probably not very wise for us."
• Green said that he expects outfielder Jon Jay (right forearm fracture) to be back around Sept. 1, give or take a week.
"I think he's probably at that point in time where he's going to start building up swinging, get to baseball activity. He's not at that point yet."
• Tyson Ross threw a bullpen session Saturday, and according to Green his ankle is feeling better and he should be good to go. Ross' recovery from right shoulder inflammation was slowed substantially after the 29-year-old sprained his left ankle while doing exercises. He has to work up to throwing to live batters before beginning a rehab stint.
• Green said that winter ball was a good option for both Cesar Vargas (flexor strain in right elbow) and Cory Spangenberg (left quad tear), who are unlikely to play with the Padres this season.
"[Nothing has been set] at this point in time," Green said. "I think those conversations are probably just a few days away, in the upcoming week or so. … I know in Spangy's case, we're going to encourage it."