WASHINGTON -- The Nationals seem likely to enter Spring Training with the No. 5 starter spot up for grabs in what will be their first rotation vacancy heading into camp in recent memory. Their usual fifth starter, Joe Ross, is still recovering from Tommy John surgery, and he could miss the entire season. Unless the Nats go out and sign a proven starter before the offseason ends, the table should be set for a Spring Training competition.
There are three candidates on the roster who are most likely to grab the final rotation spot -- A.J. Cole, pitching prospect Erick Fedde and Edwin Jackson, who reportedly signed a Minor League contract with an invitation to Spring Training. Washington considers Cole the favorite to win the final rotation spot, general manager Mike Rizzo said this week on MLB Network Radio, but it will give everyone a chance to impress during Spring Training.
Here's a look at where the three candidates stand as the Nats prepare to enter camp:
Cole
Cole is the favorite largely because of the impressive way he closed out 2017. After a few seasons of bouncing up and down between the Minors and Majors, Cole hit a stride in the second half last year. He had his best season in the Majors, with a 3.81 ERA in 11 appearances (eight starts), and he finished especially strong in his final eight games, posting a 3.00 ERA.
Cole, a 26-year old former prospect, finally began showing off some of the potential the Nationals saw when he was in the Minors. If he can continue to display that improvement during camp, Cole could be on his way to securing a rotation spot. Another key for Cole is that he is out of options, so if he is not on the team's Opening Day roster, the team could risk losing him on waivers.

Fedde
The Nationals' organization is usually filled with pitching prospects, but a series of trades the past few years has caused the need to replenish the system. Their best pitching prospect remaining is Fedde, who turns 25 in February, and is the team's No. 4 prospect as rated by MLB Pipeline. Fedde made his Major League debut in 2017, although the results were underwhelming in three starts.
Fedde gave up 16 earned runs in 15 1/3 innings (9.39 ERA), and he was eventually shut down after his velocity started to dip during his final start. But the Nationals say Fedde is healthy and has not been hindered while preparing for Spring Training, so he should be ready to compete for a rotation spot. However, Fedde will be the player with the most flexibility in this competition, someone with options whom the Nats consider as much a part of their future as their present. They could remain patient and give Fedde more time to gain experience in the Minors, unless Fedde wows them during Spring Training.

Jackson
Jackson filled the No. 5 starter role for the Nationals during the second half of 2017 after Ross got hurt. It was Jackson's second stint with Washington, after he helped lead the team to its first postseason run in '12, and he started off well. In his first eight outings in Washington last year, Jackson posted a 2.94 ERA. Even though he faded at the end of the season, he may have shown the Nats that he can still be a reliable Major League starter. If the team wants a veteran in the rotation, they could potentially keep Cole in the bullpen and make Jackson their fifth starter.