Corbin on why he took a step forward in 2018

Left-hander Patrick Corbin had a standout season pitching for the Diamondbacks in 2018. He demonstrated strength and durability, starting 33 games, winning 11 games and posting a career-best 3.15 ERA. He has started 32 or more games in four of his first six seasons.

Corbin struck out a career-high 246 batters in 2018. He said he realized that off-speed pitches were becoming very effective after strategizing with Diamondbacks hitters.

"I've learned a lot through talking with our hitters," Corbin said at Friday's introductory press conference. "I've been able to play with one of the best in Paul Goldschmidt and watching some other pitchers in our division how a slower pitch gave some hitters trouble, and it can be a free strike early in the count or something that can keep them off-balance."

Corbin said using the slider more to any hitter and being able to mix that with his fastball, has caused problems for hitters - and resulted in shorter at-bats.

"My slider has always been my pitch that I've thrown to both sides of the plate, to any hitter, so it's just something I've always had," Corbin said. "It really helped just adding that other pitch that I was comfortable throwing whenever, and the fastball command has always been something that I've thrived on as well. So just a combination of all those."

But Corbin noted there are two breaking pitches in play here - not just the slider - that are fooling hitters.

"I think my slider I've thrown similar, maybe a few more over the last year and a half maybe, because I've added the slower breaking ball," Corbin said. "I think a lot of people are counting them as the same pitch, though. I think the percentage has been kind of the same as when I used to throw the changeup a little bit more. That's another pitch I'd like to add a little bit more to my arsenal."

But for Corbin it wasn't just the different pitches he threw in 2018 that made the difference. He also credited Diamondbacks pitching strategist (and former Nationals starter) Dan Haren for helping him refine the mental side of his game.

"I credit it to multiple things, I've always just tried to be as well prepared as I could, I think every year," Corbin said. "I knew coming in I felt great that season, I was ready to go. I think the analytical part of the game, learned a lot more through Dan Haren, who was a big part of our starting staff over in Arizona. (He) helped out a lot, just knowing the right pitches to throw, when to throw them, adding another breaking ball, changing speeds, being able to control my fastball and my slider.

"So just a combination of all those things I think helped. I've had times where I've been able to do it, and last year was just easier for me to be more consistent, I'd say, and something I can continue to improve and get better as we go."

Nationals president of baseball operations Mike Rizzo, citing his scouting experience, realized how good Corbin has been since seeing him at a Florida junior college.

"I think he's finally come into his own performance-wise, but his stuff's always been there," Rizzo said. "I scouted him at Chipola Junior College and he had great stuff back then. The makeup is great, the personality is great, the competitiveness is there. An important part of this process is, he's such a great athlete. The athleticism is there. Players that are great athletes, I think, age better than players that are reliant on strictly ability. Especially pitchers. Pitchers who are athletic, I think, have a better chance of staying healthy."

And that is a critical point.

The Nats would not have signed Corbin to a long-term deal, taking a chance at a six-year package that other teams balked at, if they weren't confident Corbin would be able to maintain health for the long haul. Corbin had Tommy John surgery on March 25, 2014.

"Now pitchers are pitchers," Rizzo said. "There's always that inherent risk of a pitcher breaking down or getting hurt. But I thought this was a risk well taken. We love the makeup and the competitiveness, and we do think the needle is moving north and the stuff is getting better, and the pitchability is getting better and better."

The Nationals have also had a long history of going with pitchers post-Tommy John. Sometimes, they administer the surgery even before the pitcher works his first game with the Nats (Lucas Giolito, Erick Fedde). Rizzo says the success rate is high for post-Tommy John hurlers. The Nationals believe that is the case with Corbin too.

"I think there's 200 pitchers in the big league that have had the Tommy John surgery," Rizzo said. "It's prevalent, and I think there's a lot of success stories. Certainly, it's not foolproof. We think that the combination of all the things that is Patrick Corbin will fit us."