Dominant when healthy, Doolittle is surest thing in Nats bullpen

As our offseason coverage kicks into high gear, we're going to review each significant player on the Nationals roster. We continue today with Sean Doolittle, who had the most dominant season of his career but missed two months with a foot injury.

PLAYER REVIEW: SEAN DOOLITTLE

Age on opening day 2019: 32

How acquired: Traded with Ryan Madson from Athletics for Blake Treinen, Jesus Luzardo and Sheldon Neuse, July 2017

MLB service time: 6 years, 122 days

2018 salary: $4.38 million

Contract status: Nationals hold $6 million club option (or $500,000 buyout) in 2019, then a $6.5 million club option (or $500,000 buyout) in 2020.

2018 stats: 3-3, 1.60 ERA, 43 G, 25 SV, 45 IP, 21 H, 8 R, 8 ER, 3 HR, 6 BB, 60 SO, 2 HBP, 0.600 WHIP, 1.9 fWAR, 2.5 bWAR

Quotable: "I was feeling really good, and I was pitching better than I ever have in my career. If you had told me when I came out of that game that night that I was going to have to wait two months to get to do that again, I would've said you were crazy." - Doolittle, upon returning from his injury

2018 analysis: It was easily overlooked because of that foot injury that knocked him out for two months, but Doolittle had one of the most dominant seasons by a reliever in major league history. Seriously. Only one other reliever had ever maintained a WHIP of 0.600 or lower with a strikeout-to-walk ratio of 10-to-1 or higher over at least 45 innings: Koji Uehara, who helped lead the 2013 Red Sox to a championship.

Everyone took Doolittle's dominance for granted, because he was so consistently automatic. He surrendered runs in only six of his 43 appearances. He was perfect in 21 of those 43 appearances. He blew only one save opportunity. He threw 70 percent of his pitches for strikes.

Alas, there was that injury. It appeared to be minor when first revealed in early July. Doolittle was bummed that he wouldn't be able to pitch in the All-Star Game in D.C. but never doubted he'd be back on the mound as soon as the second half commenced. He wound up missing two months with what eventually was diagnosed as a stress reaction in his left foot. The rehab process was arduous, and every time it seemed like the left-hander was on the verge of returning, he was forced to slow things down and delay that return even longer.

The encouraging news was that once he did finally make it back in September, Doolittle was back to his old self on the mound. He was scored upon in two of his first three appearances, but then he retired 15 of the last 17 batters he faced for the season, with neither baserunner reaching via a hit.

2019 outlook: First things first: The Nationals officially must decide to bring Doolittle back for another season. Given his performance and return to health, there's no reason to believe they won't pick up his $6 million option later this week, giving them at least one sure thing in their bullpen heading into the winter.

Doolittle believed by season's end he was fully past the foot issue, and a full winter of rest should only ensure there are no lingering concerns. But folks should keep at least one eye on him next spring, just to make sure it doesn't crop up again.

On the mound, Doolittle will continue to perfect the two off-speed pitches he intended to incorporate more this year but actually used at roughly the same rate as in the past. (He threw fastballs 89 percent of the time, changeups 7 percent of the time and sliders 4 percent of the time.)

Relief pitching is a volatile business and success doesn't always carry over from one season to the next. But given what Doolittle has been able to do since joining the Nationals - 1.92 ERA, 0.760 WHIP, 91 strikeouts, 14 walks in 75 innings - it's hard not to salivate at the possibilities of what he could offer up over a full, healthy 2019 campaign.