Clearly defined roles coming to back end of Nationals bullpen

Very soon - perhaps as soon as Monday, if right-hander Brandon Kintzler gets through his minor league rehabilitation assignment this afternoon with Single-A Potomac without any issues - the Nationals will be able to set up their bullpen with the goal of shortening games to six or seven innings.

That will require the back end relievers - Kintzler, righties Ryan Madson and Kelvin Herrera, and left-handed closer Sean Doolittle - to slot into more regular roles. Kintzler and Madson will handle the seventh inning and, if necessary, the sixth. Herrera, acquired in a deal earlier this week with the Royals, gets the eighth inning to set up for Doolittle, who is on his way to making the National League All-Star team.

That was the idea when the Nats traded for Herrera, twice an All-Star with the Royals. He lengthens the bullpen, providing an effective bridge between the Kintzler/ Madson combo and Doolittle. Herrera's presence hopefully also means the remaining relievers - lefties Matt Grace, Tim Collins and Sammy Solís and right-handers Justin Miller and Shawn Kelley - won't have to pitch as many high-leverage situations or as many games overall. However, someone will have to be sent to the minors to accommodate Kintzler's return to the 25-man roster, and Collins may be the odd man out, given that carrying three southpaw relievers would be a luxury for the Nats.

"Having (Herrera and Doolittle) and Madson and Kintzler in the back end there, it's a good feeling," manager Davey Martinez said. "If you've got the lead in the sixth, seventh inning, you've got those guys coming in."

It's a far cry from spring training 2017 when the Nats went into camp with three players - Blake Treinen, Koda Glover and Kelley - competing to be the closer. Now they're about to have four guys - Herrera, Kintzler, Madson and Doolittle - with extensive closing experience on their 25-man roster.

Kintzler, who has missed 12 games while on the disabled list with a right forearm flexor strain, fills a key relief role because of his penchant for inducing ground balls from opposing batters. There is no better way to clean up a potentially messy inning than with a double play.

"Brandon throws ground balls so a situation where we need a ground ball, whether it's the sixth inning, seventh inning, whatever, he's the guy," Martinez said. "When we need strikeouts, you have the other guys. He's definitely a big part of our success moving forward."

His return may allow Martinez the option of using Madson less frequently. Madson gave up a season-high six runs in one outing - two-thirds of an inning in New York against the Mets on April 18 - raising his ERA from 1.86 to 6.97. While he's been less effective than he was earlier in the year, Madson has rebounded to post a 2.51 ERA in his 16 appearances since, and Martinez seems to be picking and choosing spots for the 37-year-old in hopes of keeping him fresher.

Herrera twice made the All-Star team in the American League as a setup man before moving fulltime into the closer's role in 2017 after the Royals dealt Wade Davis to the Cubs. Herrera is reacquainting himself with the eighth inning, though he insists there's really very little difference in pitching the eighth or ninth.

"I feel like the last two innings are very important - the most important innings in the game," he said through translator Octavio Martinez. "I always have to come out aggressive. That's just the way it is."

But he'll draw on his previous experience as a setup man to transition back into a familiar role.

"I need to prepare myself a little earlier, but in the end, it's the same job," Herrera said. "I've got one inning to pitch and I've got to do my job."

For the time being, Davey Martinez prefers slotting his relievers into roles they'll be comfortable in. But as the season moves on, and it becomes more and more critical to win games and snuff out rallies, he won't be afraid to use his two dominant backend relievers wherever and whenever they're needed.

In other words, if there are three tough left-handed hitters due up in the eighth inning and a run of right-handed batters in the ninth, Martinez could flip Doolittle and Herrera to take advantage of matchups.

"We talked about that. Not right now. As we get closer to September, something like that, those things might happen," the manger said. "It'll be a conversation I'll have with all of them. Doo gets left, right. He gets guys out, and he's done it. He's pitched in that inning and so has Herrera."