MLB Opening Day 2016: Washington Nationals' robust, but shallow, rotation

With the high-end talent it possesses, it's hard to imagine the Washington Nationals' starting rotation hinging on Bronson Arroyo. But yet, here we are.

Arroyo's injury this week -- first announced as a labrum issue, then a career-ending rotator cuff tear, later revised as an inflamed bursa sac (or not, no one really knows) -- helped to illustrate the precarious position the Nats are in. For a team built on starting pitching stars, it's dangerously thin when it comes to Major League depth at the position.

Up top, with Max Scherzer, Stephen Strasburg and Gio Gonzalez, the Nats are set. In an enviable position even. The resumes of those three are impeccable. Beyond that -- promise, and questions.

Scherzer, 31, came in last season as a big-ticket free agent and lived the part, save for a short stretch midseason. He was the architect of two no-hitters, a one-hitter, and several other gems that save for a bloop or a scratch hit could have been added to the list. It all resulted in a 14-12 record, 2.79 ERA (2.77 FIP), 0.918 WHIP, 1.3 BB/9 and 10.9 K/9. His W-L record (as we all know a poor measurement for effectiveness of a pitcher) was marred only by his teammates' ineffectiveness.

Strasburg, 27 years old and in the final year before free agency, suffered through an early ankle injury -- which later manifested as a neck strain causing a trip to the D.L. -- laboring through an up-and-down season. The big righty finished at 11-7, 3.46 (2.81), 1.107, 1.8, 11.0. The overall numbers were bolstered by a scintillating stint upon his return from the D.L.: 6-2, 1.90 with 92 Ks (and just eight walks) in 66 1/3 innings. If healthy, he should be primed to put up huge numbers in his walk year.

Gonzalez, 30, just keeps plugging along. There are few starters in the major leagues as consistent as the Nats lefty. He's never reached the upper echelon of starters -- he still walks too many to reach that plateau -- but he's as solid a No. 3 as they come. Last year he went 11-8, 3.79 (3.05), 1.423, 3.5. 8.7. The walk rate rose slightly from '14 as the K rate dipped just a bit, raising an eyebrow as something to watch.

After the big three, there's very little room for error.

The Nats let both Jordan Zimmermann and Doug Fister walk over the offseason, and instead of signing a veteran free agent to stabilize the bottom of the rotation, the only starter with an MLB resume brought in to compete was the aforementioned Arroyo, coming off two years of arm injury, on an non-roster invitation. When the veteran went down with shoulder troubles this week it should -- unfortunately for all -- come as a surprise to no one.

Arroyo's diagnosis, while not as bad as first feared, it’s still a setback for him. An inflamed bursa sac can be extremely painful and there’s no telling if rest will help, or once he starts to try to throw it won’t just flare back up, if he sticks with the "no surgery" proclamation he made when discussing a potential torn rotator cuff. This is better news than that, but still not really good news, and I don’t think this changes the Nats outlook going forward with regard to rotation depth.

Of course, by the time you read this the situation might be completely different.

By the way, we're having all this discussion over a guy that struck out just 4.9 per nine the last time he was in a Major League rotation two years ago.

That forces both Tanner Roark and Joe Ross into the opening day rotation, with no wiggle room for ineffectiveness or injury.

Both Roark and Ross are qualified for the job, but have questions. Roark, 29, was misused last season, bouncing between the rotation and pen (4-7, 4.38 (4.70), 1.306, 2.1, 5.7), but was stellar in '14 as a full-time starter at 15-10, 2.85, 1.092. Ross, 23, came out of nowhere last season to post 5-5, 3.64 (3.42), 1.109, 2.5, 8.1 in 16 games, 13 starts.

But Roark did take a big step back last season regardless of the situation, and Ross has pitched in just two fewer games at the big league level than he has at Double- and Triple-A combined. If these guys were battling for one spot in the rotation, you'd feel pretty good about your chances. But the Nats have no other choice but to depend on these guys now at the 4 and 5 spots.

A lot of times, teams will stock their Triple-A roster with players with Major League experience (think: Ross Ohlendorf, etc.). The Nats have chosen not to go that route this season, as Arroyo was the only starter with big league experience invited to camp.

As it is, the Nats only legitimate option now should they experience attrition or injury is phenom Lucas Giolito.

Giolito, 21, is a good fallback option (#sarcasm). He's the consensus top pitching prospect in the game. He's big (6'6", 255), strong, and already accomplished. He's compiled 10.0 K/9 and 2.8 BB/9 in 53 minor league games. He works 92-97 with the fastball and can reach back for more, with a plus curve and solid change. He's three full seasons out from Tommy John with no setbacks, and is primed to be in a big league rotation soon. There's nothing not to like about Giolito.

On Friday in his first start this spring, Giolito held the Mets regulars to one hit and one walk over two innings with a strikeout on a wicked 2-2 curve to catcher Kevin Plawecki.

But there are two caveats: 1) He's pitched all of eight games at Double-A; and 2) The Nats want to delay his debut until they can assure an extra season of control on the back end. So they would really like to not have to turn to him until Memorial Day at the earliest.

So what happens if the Nats experience ineffectiveness or injury before that point?

Examining the on-hand options, if Roark or Ross struggle early on, the Nats just might have to suffer until June 1. If there's an injury? Uh oh.

The only other starters on the roster even remotely qualified to step in for duty are A.J. Cole, Taylor Jordan and Taylor Hill, with Austin Voth as a long-shot wildcard.

Jordan and Hill are both soft-tossing righties that have proven to be AAAA guys -- they have reasonable success at Triple-A but are non-competitive in the bigs. Jordan, 27, has pitched to an over-5 ERA the past two seasons in the bigs in limited action. Hill, 27, has been even worse in fewer opportunities, and he hasn't been asked to start in the majors.

For Cole, this is a make-or-break year. He's a fading prospect who's been dropped off all preseason Top 100 lists at age 25, and was hammered in his big league debut last year (11 runs and 14 hits in 9.1 IP), whose K rate has dropped with each advancement (9.5 in '13, 7.5 in '14, 6.5 in '15). He depends on a sinker to generate outs, but has trouble keeping it down in the zone. It's a big league arm, but may very well be forced to the pen.

Voth is a prospect hound's dream. Unheralded from the Pacific Northwest, the scrawny Voth (6'1", 185) has put up some very good minor league numbers (career 2.70 ERA, 2.3 BB/9, 9.2 K/9 in 63 games), but has trouble maintaining velocity, to such degrees that pro scouts disagree where his fastball really sits. Some scouts have him at 92-94, others have him sit in the upper 80s. That speaks to a delivery problem that to this point has been uncorrected by the Nats development staff.

The only other remote possibility is Blake Treinen, whom the Nats have been trying to stretch out a bit in the spring. But Treinen's spot in the bullpen is precarious based on his lack of a third pitch and complete ineffectiveness against left-handed hitting (.337/.400/.471 lifetime; .336/.425/.509 in '15). That would only be exacerbated in a starting role.

The Nats top-heavy rotation is enviable, but probably not even the best in its own division. For the Nats to achieve their goals this season, the rotation has to stay healthy and get production from its 4 and 5 spots, holding on until the Nats next can't-miss phenom completes his apprenticeship in the minor leagues.