The Post’s Adam Kilgore discusses how much he expects the offseason acquisitions of starting pitcher Doug Fister and outfielder Nate McLouth to impact the Nationals in 2014. (Post Sports Live/The Washington Post)

The Washington Nationals sent two complementary major league players and a pitching prospect to the Detroit Tigers in December for veteran right-hander Doug Fister, quietly one of the better starting pitchers in baseball in recent seasons and an arm they hoped could help them reach the playoffs. Less than a month into his first Nationals spring training, however, the team’s biggest offseason acquisition has hit a roadblock. The Nationals say, and hope, it is only a minor one.

After making his first start in a Nationals uniform in a Grapefruit League game here on Sunday, Fister felt some tightness in his arm, Manager Matt Williams said. Fister underwent an MRI exam on Thursday, and the results showed inflammation in his right elbow. Fister was scratched from his scheduled second start on Friday afternoon, and right-hander Tanner Roark started against the Houston Astros instead.

Nationals officials say they are not concerned with Fister’s elbow discomfort. Williams referred to the injury as “a little inflammation.” General Manager Mike Rizzo said there is no structural damage to Fister’s elbow. Ideally, they said, Fister’s inflammation improves in the next few days and he can resume throwing. But any time a pitcher’s elbow begins acting up, there is cause for uneasiness.

“We’re not concerned about it,” Williams said. “[Fister] feels like if [we were] in season he could go and could pitch. But we’re not going to take any chances. So we’ll push him a couple days and redo the pitching schedule and make sure it feels good next time.”

Fister, 30, is expected to rest for a few days and be reevaluated, Williams said. Rizzo said the Nationals hope that missing Fister’s next start will be enough to calm the issue. “I think we’re going to skip him, and that’s going to be it,” he said.

The Post Sports Live crew debates which single player is most important to the Nationals’ overall success in 2014. (Post Sports Live/The Washington Post)

Fister was in the Nationals’ clubhouse only briefly on Friday morning when it was open to reporters but wasn’t available for comment.

“We’re going to see how it reacts,” Williams said. “He continues to get treated. No definite time frame at this point. We’re thinking about pushing him a couple days back to make sure he feels good.”

At best, Fister misses only this start or perhaps another and his elbow inflammation subsides. At worst, however, Fister could be shut down for an extended period of time. It is too early to tell how Fister’s elbow issue will affect his status for the season. Teams are generally optimistic at first about arm injuries, and rest is the common first treatment.

Some pitchers with elbow inflammation have returned after rest, and others have needed surgery to alleviate the cause of the pain. Last spring, Los Angeles Dodgers right-handed starter Zack Greinke, for example, had inflammation in his right elbow but no structural damage. He received an injection of platelet-rich plasma to accelerate healing, didn’t need surgery and made his first start of the regular season on April 5. He finished the season with a 15-4 record and a 2.63 ERA that was among the National League’s best over 1772 / 3 innings.

Other pitchers, however, have sat out longer. In the spring of 2012, Nationals reliever Drew Storen had elbow inflammation but an MRI found no structural damage. In April, nearly three weeks later, Storen had surgery to remove a bone fragment in his right elbow. Storen returned to the Nationals in mid-July that season.

This appears to be the first time Fister has dealt with elbow issues in his career. He has had shoulder, side and rib injuries in the past, but he was healthy last season and made 32 starts for the Tigers. Fister is known to be a workhorse, and for his tough mentality. He was once hit in the head by a line drive in Game 2 of the 2012 World Series against the San Francisco Giants and stayed in the game.

The towering 6-foot-8 right-hander has been one of the best groundball pitchers in baseball and, according to some advanced metrics, was among the most valuable starters over the past three years. In that span, he has averaged 196 innings a year with a 3.30 ERA.

Nationals officials and teammates were thrilled about their upcoming first season with Fister. Baseball analysts have considered the Nationals’ trade for Fister among the best of the offseason and a marked upgrade to their rotation. The Nationals sent utility man Steve Lombardozzi, left-handed reliever Ian Krol and left-handed pitching prospect Robbie Ray to Detroit on Dec. 2. Fister is due $7.2 million this season and is under team control through 2015.