The Chicago Cubs will continue to try to improve their starting rotation, and part of that process may be to trade top starter Matt Garza for depth.

"I don't think we are done," Cubs president Theo Epstein said Friday after trading Sean Marshall to the Cincinnati Reds. "I do think we still need to build more depth on the starting pitching front, both in the big leagues and minor leagues.

"But it doesn't happen overnight. You have to make sacrifices. Just like moving Sean Marshall, who was certainly an asset for the 2012 club."

Another sacrifice would be dealing Garza, who led the Cubs with a 3.32 ERA and 197 strikeouts and tied for the team lead with 10 wins.

"Matt Garza is the type of pitcher you want to build around," Epstein said Friday. "He's a proven top-of-the-rotation guy, a proven performer in the playoffs. I think last year he had his best season, all things being equal.

"It's hard to find top-of-the-rotation guys, so if you have them, and if there's a way to keep them around, that's always compelling for the club. With that said, we've been honest. We are in a mode where we have to listen on everybody. And if there's a way to improve the long-term outlook for this club in a significant manner, we can't look past opportunities."

Epstein and general manager Jed Hoyer talked to numerous teams about Garza during the winter meetings, including the Texas Rangers, Arizona Diamondbacks and Kansas City Royals, according to major league sources. Currently, the New York Yankees and Toronto Blue Jays have interest in Garza, after both missed out on posting for Japanese pitcher Yu Darvish.

"We aren't in a situation where we have to do anything with Garza," Epstein said. "But generally we are in the business right now of taking our short-term assets and turning them into long-term assets. In the case of Sean Marshall, that ended up happening in a trade. We turned a short-term asset in Marshall into what we hope will be three long-term assets (in Travis Wood, Dave Sappelt and Ronald Torreyes)."

It doesn't appear Epstein is closing the door on the possibility of extending Garza, who made $5.9 million in 2011 and will make $7 million to $8 million through arbitration in 2012. The Cubs have him under contract through 2013.

"In the case of Matt Garza, perhaps nothing happens, or perhaps we can turn him into a long-term asset by extending him on a deal that makes sense for everybody," he said. "We'll listen, because there's always an active trade market for top-of-the-rotation guys with multiple years of control."

Bruce Levine covers baseball for ESPNChicago.com and ESPN 1000.