The Washington Nationals’ bullpen is still the worst in baseball, considering its 6.27 ERA, but they will need their relievers to turn a corner to have any chance this season. This week, we’ll take a look at those seven relievers — some clicking, some not, some closer to figuring it out than others — by zeroing in on one each morning. We touched on right-hander Tanner Rainey on Tuesday. Here’s more on Wander Suero:

What the Washington Nationals know about Wander Suero is important and, at this point, over-discussed: The right-handed reliever has a very good cut fastball. He can use it to pitch inside to left-handed hitters. His arsenal revolves around that pitch.

But what the Nationals don’t know, 30 appearances into Suero’s first full major league season, has defined him in recent weeks. He has struggled in the second game of back-to-back appearances. His cutter velocity — sometimes in the mid-90s, sometimes not — has curiously fluctuated from one outing to the next. He is still figuring out how to best use the pitch against right-handed hitters. And, if that wasn’t enough, his secondary pitches are a work in progress.

This has made it hard to trust Suero as a high-leverage reliever, something the Nationals would very much like to do. He’s been, in short bursts, a reliable seventh- or eighth-inning option. Then he confounds Manager Dave Martinez with a misplaced two-strike pitch, or a sagging cutter, or an all-out lack of command. Martinez has a hand in this, too, as it’s his job to figure out how to best use Suero moving forward. The bullpen will need him as it looks to turn a modest turnaround into a new reality. The group has a 3.05 ERA in June, the fourth-best in baseball, and that’s with Suero still figuring it out. The 27-year-old has a 6.35 ERA this year, a nod to his inconsistency, and has given up an earned run in each of his last two outings.

“We tried a lot of different things,” Martinez said. "He’s working really hard in the weight room and getting stronger, that’s a plus. Eventually this is something that he needs to grow into. Because if you’re in the bullpen, for me, you have to pitch two or three days in a row and be consistent.”

Both the Nationals and Suero have looked at a lot of different factors — preparation, warmup routine, rest-to-pitching ratio — to see why he’s faltered in back-to-backs. Suero isn’t sure what the issue is, but noted that, naturally, his arm feels tired if he throws a lot of pitches the first day. His three back-to-backs since in the last few weeks are an indication.

Suero notched two scoreless appearances on May 26 and 27, and threw just eight pitches in the first one to record one out. But higher front-end pitch counts seemed to hurt him in the next two back-to-backs. He threw 19 pitches while not allowing a run in 1 1/3 innings on June 4, and then gave up a solo homer the next day. He threw 12 pitches to complete a scoreless frame on June 7, then yielded a walk, single and run a day after that. The indication is that fatigue is the prominent reason for subpar results.

And yet Suero, owning his mistakes, feels he can be better either way.

“You come out the next day and you’re a little bit tired and you give your 100 percent, but you can’t give it your all because you are a little fatigued,” Suero said through a team interpreter Tuesday. “That’s probably the biggest challenge and difficult part about [pitching back-to-backs], but I can still work on it and improve.”

To do that, Suero is tinkering with his curveball and changeup to make his cutter as effective as possible. He throws his cutter 69 percent of the time, according to Fangraphs, and his change-up usage is way up from a season ago. He’s throwing it at a 20 percent clip — after finishing 2018 at just 4.4 percent — and it’s taken over the curve as his second option. Suero has twice gotten in trouble with his curve this season, giving up a game-winning double in one instance and a backbreaking home run in another. Martinez even called it his fourth-best pitch , considering a four-seam fastball he hardly ever throws, after Suero gave up that double in a loss to the Pittsburgh Pirates on April 14.

That’s all helped Suero give the change-up a more prominent spot in his repertoire. He almost exclusively uses his cutter when ahead in counts, according to the pitching analytics site Brooks Baseball, but has grown more confident using his changeups against left-handed batters. He’s been a reverse-splits pitcher this year — with lefties having less success against him based on on-base-plus slugging percentage — which is something Martinez likes to bring up. The cutter and changeup play well to lefties because they move in the same tunnel until splitting in opposite directions about halfway to the plate.

The challenge, then, is how to attack right-handed hitters with a less-obvious approach for his cutter. The cutter is at its best when running in on left-handed hitters. To righties, Suero has tried throwing it inside by basically starting it at their body. He has also tested it on the low-and-outside corner, dropping it out of the zone like a slider. Figuring out the best location for that pitch will determine how he sequences his breaking ball and change-up. And that could a long way as both Suero and the Nationals try to solve him.

“That cutter is a gift pitch, it’s something that you just can’t teach or develop,” said catcher Yan Gomes. “So with Wander, you want to make sure that the other pitches aren’t taking away from it. You want to throw them just enough so hitters have to think about it, and then get back to the cutter, and then you can ...”

Gomes had been talking about utilizing Suero’s cutter for four straight minutes. He paused, took a deep breath and apologized for getting too technical.

“We just have to figure it all out," he added. “And then he is going to be really freaking good.”

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