Fister, 29, went 14-9 with a 3.67 ERA for the Tigers last season, striking out 159 and walking 44 in 208 2/3 innings. He combined with Max Scherzer, Justin Verlander and Anibal Sanchez to give Detroit a highly productive starting staff.
With addition of Fister, the Nationals have arguably the best rotation in the National League East.
"This is an exciting day for the Washington Nationals," said general manager Mike Rizzo in a statement. "We feel we've added a talented, young veteran to our starting-pitching corps. Doug is battle-tested through playoff experiences, and the depth he brings to our staff is exceptional. We are thrilled to welcome him aboard."
The Nationals and Tigers had been in discussions about a trade for quite some time. In fact, according to Tigers GM Dave Dombrowski, the Nationals inquired about several of Detroit's pitchers. For weeks, it was reported that the Nationals had interest in Scherzer.
"I think it's a situation where, realistically, Verlander and Sanchez are here for the long term," Dombrowski said. "[Drew] Smyly, we look at as a guy ready to step in. Scherzer, it would be difficult to [trade]. We've had inquiries and interest in all of them.
"Washington asked about some of our other starters. This is the guy at the end that they had focused on ... even going back a couple weeks."
One American League scout viewed the trade between the Nationals and Tigers as "a steal" for Washington. The scout was surprised the Nationals traded so little to acquire Fister: "If you want a guy [like Fister], you have a to give up a little bit more."
"He is a strike thrower, for one thing. He competes," the scout said. "I think he will do a better job than Haren did for the club. He is not a hard thrower, but the thing is, he will give innings. I think that's probably what the Nationals were looking for from Haren last year. He wasn't able to do that until the last part of the season."
In five seasons with the Mariners and Tigers, the 6-foot-8 Fister is 44-50 with a 3.53 ERA. He has struck out 6.3 batters per nine innings but combined that with a rate of 1.8 walks per nine. Fister also has produced a ground-ball rate of almost 50 percent over his career, and his 54.3 percent mark last season was the fourth highest in the Majors.
Fister, who made $4 million last season, has two years of arbitration remaining and figures to get a decent raise this offseason. Keep in mind that after trading for Gonzalez in December of 2011, the Nationals promptly signed him to a five-year, $42 million extension.
Lombardozzi spent three seasons with the Nationals, playing mostly second base but also left field, third base and shortstop. The 25-year-old hit .259/.278/.338 with two home runs and 22 RBIs in 118 games last season.
"He is what he is," the scout said. "He is a utility-type player. He is a guy that is not going to hit for power. As you know, the Nationals are looking for guys that have home run or gap power. He is just a utility guy. Primarily, he is a second baseman. I think he was misplaced in the outfield."
Krol made his big league debut last season. He got off to a great start with the Nationals, allowing two runs in 11 2/3 innings during the month of June. After that, he had a 5.74 ERA and then-manager Davey Johnson stopped using him after Sept. 17. Krol could start the season in the Minors without a good performance at Spring Training.
"He is just another guy. I don't think you will see anything better than that," the scout said.
Ray was ranked the Nationals' No. 7 prospect in 2013 by MLB.com. The 22-year-old split 2013 between Class A Advanced Potomac and Double-A Harrisburg, going 11-5 with a 3.36 ERA and 160 strikeouts in 142 innings.
The Nationals have to figure out who will be the fifth starter in the rotation. Tanner Roark, Taylor Jordan and Ross Detwiler are candidates. It would not come as a surprise if just Roark and Jordan battle for the spot. The team is seriously considering Detwiler for the bullpen.