With Chien-Ming Wang in the fold, the Nationals have a commodity all teams pine for: starting pitching depth. In Mike Rizzo’s eyes, the Nationals have “eight or nine” starting pitchers who could join their rotation at some point in 2012, and some pitchers who could pitch in the majors will spend the majority of their year in the minor leagues.

After Wang’s signing became official today, the Nationals control the 2012 contract rights to eight pitchers who started for them in the majors in 2012: Stephen Strasburg, Jordan Zimmermann, John Lannan, Ross Detwiler, Brad Peacock, Tom Milone, Tom Gorzelanny and Wang.

“I really like the way the rotation is set right now,” Rizzo said. “We have great depth there. We have great talent. We have some top-of-the-rotation guys. We have some middle-of-the-rotation guys. We have some back-of-the-rotation guys. We’ve got great depth in our minor league system. We’ve got guys that probably should be pitching in the big leagues this season and may not be. I think that’s a tribute to where we’re at.

“With that said, we’re certainly not satisfied ever. You can never have enough quality starting pitching. It hasn’t changed our long-term offseason outlook that we’d like to improve our starting rotation.”

Even with their stable of pitchers, the Nationals will continue to pursue a starter on the free agent market. Individuals familiar with the Nationals’ plans expect them to target Chicago White Sox left-hander Mark Buerhle. Today, Rizzo described the kind of pitcher he would like to sign.

“The pitcher we’re looking for is a good leader type of guy who can throw a lot of innings,” Rizzo said. “He’s shown he can win in the big leagues and really lead our staff, not by having the best stuff on the staff, but by showing how to be a professional and how to be a winner and how to pitch 200 innings in a season many, many times. That’s kind of the guy we’re looking for.”

That’s just about a point-by-point description of Buerhle, 32, who has exceed 200 innings pitched in all 11 of his full major league seasons despite a fastball that averages in the mid-80s. He commands respect from teammates, the kind of veteran Rizzo has shown he loves having around. Buerhle has spent his entire career with the White Sox, but he has said the National League intrigues him.

The Nationals have another motivation for adding pitching depth. Rizzo wants to acquire a center fielder who can bat leadoff effectively, but the thin free agent market may demand they trade for one. The Nationals are the rare team that could comfortably trade major league pitching — not that they want to.

“We have enough pitching depth that we could trade off of our pitching depth,” Rizzo said. “We also have depth at the other positions with a deep minor league system. We certainly have the depth to make a trade if we tried to do so. You can never have enough pitching. It’s taken us a long time to assemble a deep farm system that we could be proud of. We certainly don’t want to rid ourselves of that. It’s important to keep the depth.

“Pitching depth often and quickly becomes pitching need, when an injury happens or that type of thing. I’m often afraid to trade off of pitching depth to fill another one of our needs because pitching is so scarce in the game right now and so valuable.”

The Nationals will need at least a sixth starting pitcher at some point next season even in the unlikely event their five starters stay healthy all year. Stephen Strasburg will pitch with an innings limit, like Jordan Zimmermann in 2011. Still, Rizzo feels that’s not a major factor in his offseason plan.

“We feel we have at least six or seven quality guys that we could call upon to start in the major leagues,” Rizzo said. “We feel we’re about eight or nine deep as far as starting pitching depth in our system. The Strasburg thing doesn’t come into play that much for us right now. He’s going to get quite a few innings in. We feel we go well beyond six or seven guys that we can count on starting for us.”