Age on Opening Day 2016: 22
How acquired: Three-team trade with Padres, Rays in December 2014
2015 stats: 16 GS, 5-5, 3.64 ERA, 76.2 IP, 64 H, 33 R, 31 ER, 7 HR, 69 SO, 21 BB, 3.42 FIP, 8.1 SO/9
2016 storyline: Joe Ross was undoubtedly the most pleasant surprise in a starting rotation that largely disappointed in 2015, as he rose from relative obscurity in the minor leagues to suddenly becoming somewhat of a steadying presence.
Previously known as the "other guy" who came with Trea Turner in the Steven Souza trade, the 22-year-old Ross was called up in the middle of the season and showed poise well beyond his years. His record was a modest 5-5, but he allowed two or fewer runs in 11 of his 16 starts and owned a 69/21 strikeout-to-walk ratio.
The question heading into 2016 is whether or not he can prove that he isn't a flash in the pan. More importantly, he has to show that he can take another step toward becoming a longterm fixture in the rotation. He only has 16 starts under his belt and teams will surely have a better handle on his pitching arsenal, so it'll be incumbent upon him to evolve as hitters learn his tendencies.
Best-case scenario: This is tough to tackle since Ross's ceiling is unknown — he was a former first rounder, but wasn't touted as a top-of-the-rotation guy — but the Nats would be overjoyed if he somehow progresses to the point where he's the team's third best starter behind Max Scherzer and Stephen Strasburg. If Ross were to achieve that and the aforementioned Turner became the everyday shortstop, that'd mean Mike Rizzo yet again came out on the winning end of a trade.
Worst-case scenario: Ross is still a young pitcher trying to find his way in the major leagues, so it's entirely possible that he regresses as opposing teams get more of a look at him. After all, it was Turner that was the centerpiece of the Souza trade, not Ross.
While he never really had a truly awful outing in 2015, Ross tended to struggle more against the NL's upper tier. His worst start of the season came against the Dodgers on Aug. 11 during a key west coast swing, when he allowed five earned runs (including four walks) in just 4 1/3 innings. Outside of that one blip, Nats fans haven't really seen Ross's floor. But that doesn't mean he won't struggle as he continues to develop.
Most-likely scenario: There isn't much of a sample size to make a well-informed prediction, but it wouldn't be surprising if Ross turns into a reliable starter in what will be his first full season in the majors. Will he have "ace" stuff? Probably not, but the Nats don't need him to, either.
For what it's worth, Fangraphs projects that he'll post a 3.86 ERA over 27 starts. If Ross turns in that effort in 2016, the Nats will surely take it.