On the importance of rotation depth

The Nationals' acquisition Monday of Rogelio Armenteros didn't generate much buzz, nor should it have. A 26-year-old right-hander with five games of big league experience claimed off waivers? That's not exactly blockbuster material.

But the move did offer up a reminder of an important but oft-overlooked area of concern for the Nationals and all clubs: rotation depth.

Armenteros isn't going to make the Nats rotation out of spring training. If he somehow does, a bunch of things have gone horribly wrong. But there's a reasonable chance the righty will start a game for the Nationals at some point in 2021, because history shows they're probably going to need to reach that deep into their pool of reserve pitching during the season.

As much as we talk about the importance of a quality, five-man rotation, truth be told, every team needs a lot more quality arms than that. And they don't just need a decent sixth or seventh starter. They need 10 or more who can be called upon per year.

Over the last four seasons, the Nationals have used an average of 10.5 starting pitchers. They only used nine this year, though that number surely would've gone up had they played 162 games instead of 60. They maxed out with 12 starters in 2018.

And most of those replacement arms are needed for more than one spot start here and there. On average, the Nationals have given 30.25 starts to pitchers other than their top five rotation members during the last four seasons. Add those all up, and that's roughly the equivalent of a No. 6 starter who pitches every fifth day for six months.

Not surprisingly, those extra starters haven't fared especially well. This year, they went 2-5 with a 5.65 ERA and 1.535 WHIP across 13 starts. The 2019 crew was a respectable 8-6 with a 4.26 ERA and 1.395 WHIP in 27 starts. But the 2018 extra starters (6-11, 6.07 ERA, 1.543 WHIP) and 2017 extra starters (8-14, 5.57 ERA, 1.565 WHIP) were quite awful.

Think about the importance of those games. That's one-sixth of a season with a replacement starting pitcher on the mound, and the Nationals have lost far more of those games than they've won.

The Nats actually thought they were well-covered in the rotation depth department entering the 2020 season. But when Joe Ross opted out and Stephen Strasburg needed wrist surgery after only two starts, they were forced to put Austin Voth and Erick Fedde in their five-man rotation for the bulk of the season. That bumped rookies Wil Crowe and Ben Braymer, plus journeyman Paolo Espino, into the roles of replacement starters, and the results weren't great.

How's the organization's depth look heading into 2021? Better, if general manager Mike Rizzo can acquire a quality No. 4 starter to replace Aníbal Sánchez, and if all the other regular rotation members are healthy entering the season.

If those things happen, the Nationals should go into next season with Voth and Fedde as their No. 6 and No. 7 starters, then Crowe, Braymer and Armenteros as the No. 8, No. 9 and No. 10 guys (in no particular order). We could also see prospects Seth Romero, Tim Cate, Steven Fuentes and Joan Adon make their case for big league starts, if needed.

Will that be enough quality depth to make it through a 162-game season? Obviously, the Nationals first and foremost need their top five starters to stay healthy and pitch well enough to limit the number of replacement starts necessary in the first place.

But even in a best-case scenario, the Nats almost certainly will need to cobble together 20 or more starts out of that group of replacement pitchers next season. And though they don't need that group to be elite, they do need it to be good enough to give them a chance to win some games on nights when they can't send an elite starter to the mound.