Blake Treinen finished the 2015 campaign with a 3.86 ERA, a 3.49 FIP, 32 walks (4.26 BB/9) and 65 Ks (8.65 K/9) in 60 games and 67 ⅔ innings pitched.
The obvious issue, which the 27-year-old reliever acknowledged this winter, was that he couldn't get left-handers out, at least not consistently.
While he held right-handed hitters to a .184/.276/.216 line, left-handed hitters had a combined .336/.425/.509 line against him.
"Obviously there were some issues with consistency against lefties," Treinen told reporters this winter.
"That to me is the biggest glaring issue that I need to fix. There are times when things went really well, there are times when things went pretty darn bad. So the consistency side of things is my biggest focus for this offseason."
It wasn't any one thing he identified that he needed to work on, Treinen explained.
"You make good pitches some times and they put good hits on it and then you make terrible pitches and they make you pay for it, so I think it's just a matter of knowing how to attack a little better and then executing those pitches."
So how did it go this Spring? Right-handed hitters were 3 for 15 (.167 AVG) with six Ks against Treinen.
And it's a small sample size of just 4 ⅔ innings pitched, or just 14 left-handed batters, but the right-handed reliever looked strong, holding left-handed hitters to one hit (.077 AVG) and one walk.
Overall on the Spring, Treinen threw 8 ⅔ scoreless. His new manager was impressed with what he saw from the sinker-balling righty.
"This guy can give us two or he can give us a specialty situation," Dusty Baker told reporters in late March.
"Anybody that throws as hard as he does, and anybody that can throw that sinker, man, that's a team and a manager's best friend.
"He can [get] me out of trouble with one pitch. Any time you can get two outs with one pitch, then that's a primo situation."
Treinen said he was happy with the results against left-handed hitters after a two-inning outing on March 16th.
"I think I've had some good success against lefties for sure," he said.
"Continue to improve though, at the same time. Every day is another opportunity to get better. Tomorrow I'll go back to work on trying to execute pitches the right way so I can be consistent."
Impressive as he was, he was still on the bubble until Friday night when the Nationals made their final roster decisions, which included naming Treinen as part of the Opening Day relief corps.
"I tell you, his sinker's something. His slider is working big-time. He's throwing the ball well. ... He knew and [pitching coach] Mike [Maddux] knew what we had to work on in spring training. I tell you, whenever somebody talked trade with us, they always mentioned Treinen."
While the Nationals stretched Treinen out this Spring, having him go multiple innings in three of his five appearances, it was always with the knowledge that it was easier to do that than take the opposite approach.
"We'd rather not throw Blake, if we could, multiple innings because that kind of negates him for the next day," Baker explained.
"But the game's going to dictate that situation and who the hitters are," he said.
If there is one thing the Nationals still want Treinen to change, the Nats' new skipper explained, it's that they'd rather have him get a little bit meaner on the mound.
"He’s looking very good," Baker told reporters, including Washington Post writer James Wagner.
"He has a great demeanor. But so far, he’s had a good demeanor and things are going real well. He’s a fine young man with a great body, good looking. He’s a jewel of a person. He’s a good looking guy. I just kinda urged him to have a little more dog in him this year."
Maddux told the WaPost reporter that he focused on getting Treinen to simplify things.
"We have simplified a little thought process. Use your go-to’s. Here’s how you protect your go-to’s. Use both sides. Pitch with an attitude. And he’s really taken it out there, and he’s been pretty good."
"Treinen, I mean, he had an outstanding Spring," Baker said after the announcement on the final roster decisions was made.
"He's one of our back end of the bullpen guys and he's a guy that can throw up a double play or get a strikeout when you need it and it appears that he's maturing in front of our very eyes. He's gaining confidence every day."