Purke will wear No. 47 and start working out in the team's Spring Training facility in Viera, Fla. During that time, the team will determine when he will start pitching in games. Purke has spent the summer throwing in bullpens and is ready to throw about two to three innings.
Purke, who throws a fastball, curveball and changeup, said his pitching style is similar to Dodgers left-hander Clayton Kershaw and Phillies left-hander Cole Hamels.
"I have the same build, similar style, so I kind of watched those guys, and I've been fortunate enough to meet both of them, talk to them and learn about their careers and what has been successful for them," Purke said.
Purke received a Major League contract and was put on the 40-man roster on Monday. It was reported that Purke received a four-year, $4.4 million deal, but a source said the dollar figures were less than what was reported.
After being drafted, Purke came to Washington to visit the Nationals in early July before the All-Star break and came away impressed with what he saw from the organization.
"I came up here. They come highly recommended," Purke said. "I've seen the things they have done the last few years with the prospects they have brought in and the Major League players as well. This organization is going to be very strong and they are building. They are going to be a serious team to deal with in years to come and I wanted to be part of that and hopefully be a helpful piece in the puzzle.
"When I got to [Texas Christian University], I kind felt the sense of this is home. This is where I can call home and I can fit in with these people and be a part of this group. Throughout the days I was in Washington before the All-Star break, I got the same similar feeling [after] I was able to talk to the owners, be around the stadium, see the fans and stuff. I know this feeling and it was a good one and that's why I felt that way."
The left-hander has the ability of a top-round talent -- he was selected No. 14 overall by the Rangers in 2009, coming out of high school -- but he came with injury concerns.
Purke had a dominant freshman season that saw him go 21-1 for TCU, but elbow bursitis shut down the sophomore after 11 starts this season.
Before agreeing to terms, Purke took a physical and pitched in front of general manager Mike Rizzo and a member of his staff. Purke did something that is rarely done by Draft picks. He allowed the team to do an arthrogram and shoot dye into his body in order for it to get a clear evaluation of his status. Purke showed that he was healthy and the team was willing to sign him.
"The only thing I could do is lay it out there and say, 'Do what you want to do. Look at the test, get your own assessment of it and then we could talk,'" Purke said. "I knew I was healthy, that I was fit again. I had to prove it."
Purke and the Nationals had the parameters of a deal in place by Saturday night into early Sunday morning.
"It was more dialogue between the two parties. We are just more open and up front," said Purke's agent, Peter Vescovo. "That's the way Matthew and his family wanted it to be. We were going to be straight forward and honest. People asked, 'Why would you shoot the dye, why would do this?' That's the way these Texas people are. They will put everything out there, show you what they are about. I think Mike and I kind of agreed that we are going to move forward with it. Luckily, it worked out. "
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.