On today's flurry of roster moves, plus injury updates (Nats down 6-0)

MILWAUKEE - Though they got one key player back from the injured list today, the Nationals placed a key reliever on the IL. All while watching two players hurt during Monday night's loss avoid the IL (for now) and another key regular who has been on the IL more than a month take an important step forward his recovery.

Oh, they also demoted their top prospect and recalled one of their top young starters, making him a full-time reliever for the first time.

Yeah, it's been an eventful day. Just as so many others already have been for the Nationals in 2019.

Anthony Rendon's return from the IL 17 days after he was hit in the left elbow by a pitch gives the Nats a significant boost, both at the plate and in the field. He's back in his familiar spot in the lineup, batting third, and also back at third base, which should do wonders for the club's defensive woes.

Rendon's return also allows the Nationals to move Wilmer Difo back to shortstop, and in turn demote struggling Carter Kieboom to Triple-A Fresno. The Kieboom decision was disappointing for the organization, which hoped the 21-year-old could handle the pressure of his first stint in the big leagues. But after watching him go 5-for-39 with two homers, four walks, 16 strikeouts, a -6 Defensive Runs Saved rating and -0.9 WAR in only 11 games, the team had little choice but to make the move.

"There's a lot of good players in this game that have been optioned before, and come back and done really well," manager Davey Martinez said. "I've got all the confidence in the world. This organization does. He's one of our top prospects. He goes back down there, gets to playing, relaxes a little bit. ... He's going to be back, for a long time."

The Rendon-Kieboom swap took care of one expected roster transaction. The Tony Sipp-Erick Fedde transaction, however, was unexpected.

Sipp landed on the 10-day IL with a right oblique strain. The left-hander revealed he had been dealing with it "for about a week," but it became more noticeable during his appearance Monday night. Rather than try to push through it, the Nationals told Sipp to shut it down now and come back fully healthy in short order.

"We've got to get him right," Martinez said. "It was a long conversation. He wanted to fight through it. But I told him: 'We need you for longevity, not just for a short stint. Let's get you right.'"

Sipp, who didn't sign with the Nationals until mid-March and had only two weeks to prepare for the season, owns a 6.00 ERA in 17 appearances, though he has only totaled nine innings. Lefties are hitting .292 (7-for-24) against him, though righties are batting just .182 (2-for-11).

"If it's any other time, I feel like I can probably fight through it," Sipp said of his injury. "But it seems like a perfect time to just do nothing, let everything settle. Honestly, just try to get everything back under me, because I've been dealing with this and I'm trying to play catch-up since spring."

With an opening in their bullpen, the Nationals decided to recall Fedde from Double-A Harrisburg, only nine days after he was sent down following an impressive, four-inning relief appearance in Washington. The 26-year-old, long considered the organization's top starting pitching prospect, made only one relief appearance during his brief time back in the minors - he threw one scoreless inning Saturday - so he's fresh and he's embracing this new role.

The Nationals briefly tried to convert Fedde to a reliever in 2017, but abandoned those plans after a couple months. Both sides feel he's better prepared for the switch now.

"I honestly just think I'm a better pitcher at this point," he said. "I was a lot younger when we tried it that last time. I feel like I've just developed a little more, and maybe have a better attitude going into it this time."

Martinez said he'll have to ease Fedde into situations, much as he did with fellow converted starter Joe Ross in recent weeks. He won't pitch back-to-back days yet. But he will be used in situations of consequence as the club tries to fix its woeful bullpen.

"He has to buy in," Martinez said. "This is something we talked about with him. And the conversation was: 'If you're willing to do this, you can help us right now.' And he did. He went down there, pitched an inning in the bullpen, and that's how we're going to use him."

Those were the extent of the Nationals' transactions today. They managed to avoid placing either Yan Gomes or Andrew Stevenson on the IL after both players departed Monday's game with injuries.

Gomes, who took a fastball off his left forearm, had a large welt to show off today but was hopeful of being able to come off the bench if needed. Stevenson, who came down with back spasms after diving into first base trying to beat out a grounder and then swinging in his next at-bat, is "still a little stiff," according to Martinez, and is day-to-day.

Meanwhile, Trea Turner took a light round of batting practice on the field today for the first time since he fractured his left index finger April 2. Turner still isn't taking full swings, and he isn't making full throws from shortstop, but he's making progress and appears to be perhaps two weeks away from rejoining the Nationals lineup.

Juan Soto also is making progress in his return from back spasms. The 20-year-old outfielder played catch on the field today, and club officials believe he'll be ready to return Saturday when he's eligible to come off the IL.

Update: What was a tense pitchers' duel, with Stephen Strasburg cruising and two Brewers pitchers doing likewise, completely unraveled in the seventh inning. Strasburg loaded the bases with one out, and though he struck out Eric Thames, he then watched helplessly as Lorenzo Cain cued a ball down the first base line, clearing the bases and giving Milwaukee a 3-0 lead. Then Dan Jennings entered and everything fell apart. The lefty didn't retire any of the four batters he faced, blowing this game wide open. Scoreless in the middle of the seventh, it's now 6-0 at the end of the seventh.