WASHINGTON -- The Nationals made it official Friday, signing free-agent right-hander Dan Haren to a one-year, $13 million contract.

Haren joins a solid rotation that includes Stephen Strasburg, Jordan Zimmermann, Gio Gonzalez and Ross Detwiler. Haren effectively replaces Edwin Jackson.

"Yes, I had quite a few other choices, but the Nationals kind of fit for me," Haren said during a conference call. "The momentum started to pick up Sunday or Monday. ... Obviously, the club they have -- winning close to 100 games and the majority of the people coming back -- I felt I could fit well with the rotation, just being able to eat innings and give the team a chance every time out. With the offense that we have, we have tremendous defense, great bullpen, I think we could only improve with what we did."

Of the pitchers available this offseason, Haren was Washington's top choice. General manager Mike Rizzo acknowledged that Zack Grienke was the top free agent from a pitching standpoint, but it was pretty clear the team was not in the mix for Grienke's services.

"Haren was our primary target going into it. We showed our interest right away. After meeting with his agents in Nashville, we got the deal finalized, pending a physical," Rizzo said.

Since 2005, Haren has tallied seven 200-inning campaigns and averaged 220 innings per year. In that same eight-season span, Nationals pitchers have posted just four 200-inning efforts.

Haren, who has ranked among his league's leaders (top 10) in strikeouts per nine innings on six occasions and walks per nine innings five times, owns career per nine inning rates of 7.6 strikeouts and 1.9 walks. That stellar 4.0/1 strikeout-to-walk ratio that leads all active pitchers.

Haren, a three-time All-Star, spent the last two-plus seasons with the Angels. He missed time in 2012 because of injuries to his back and hip, but made 30 starts and won 12 games.

The Angels declined Haren's 2013 option and bought him out for $3.5 million after trying to trade him to the Cubs last month for Carlos Marmol, a deal that was reportedly called off because Chicago did not like the medical reports on Haren's hip.

But Haren said he is healthy, plans to lose some weight, perform core exercises and improve his flexibility.

"In regards to my health, I know it was question mark for a lot of people," Haren said. "If it makes anyone feel better, there were lot of teams that were interested in my services. I obviously passed the physical. I feel great right now. I understand teams had concerns, otherwise, I would have gotten a three- or four-year deal. That said, I think I have a lot to prove this [coming season]. I'm very confident that I'm going to stay healthy. I feel great right now. I'm probably going to start throwing in a week."

Haren, who started his career with the Cardinals in 2003 before playing three seasons with the Athletics and 2 1/2 years with the D-backs, will bring a veteran presence to Washington's young staff.

"I will do all I can," Haren said. "I'm pretty open with talking to guys even with teams I've been with in the past. I think everyone feels comfortable talking to me. This is my fifth team and it's going to take time. I'm not going to be myself right when I get to Spring Training, but it takes time to learn guys.

"It's going to take a little time. I'm sure we'll jell together quickly. With teams I've been with in the past, I think it's important for the starting staff to be close to each other -- No. 1 fans when they are out there, always be on the bench, pulling for the guys. It's fun when you have a cohesive unit like that. You can turn the rotation over with a lot of success.

"A rotation like [the Nationals], the hope is you don't get in any long losing streaks," Haren added. "Any particular guy can be the stopper. On the flip side, when guys get going, I'm sure there will be nice winning streaks. You can put all those things together, the expectations are definitely high.'