MESA, Ariz. — Oakland found its closer in Blake Treinen last summer, and its bullpen transformation continued when it acquired offseason targets Yusmeiro Petit and Ryan Buchter this winter.

For a team that had 25 blown saves, one short of the major league high, and converted only 58 percent of its save chances a year ago, it is another step forward.

“We feel like we’re a lot better,” A’s manager Bob Melvin said, “and we feel like we have a deep bullpen, too.

“We have a number of guys who can give us multiple innings now, where you are not having to go through one-inning guys and use so many guys during the course of a game.”

Everything starts with the closer, of course, and Treinen is ready to continue that role after recording 13 saves following his acquisition from Washington for veteran relief arms Sean Doolittle and Ryan Madson in mid-July.

Treinen was used in a setup role upon arriving in Oakland before being given the ninth inning almost exclusively in early August. It took.

He converted his final 12 save chances last sesaon, starting when he finished off an 11-10 victory over the Los Angeles Angels with two strikeouts and a weak popout on Aug. 6.

Treinen had a 2.36 ERA in his 24 appearances from that point, with 31 strikeouts in 26 2/3 innings.

“That’s my goal, to pick up where I left off last year,” said Treinen, 29 “My goal is to go out and get outs and give this team the best chance to win. Just try to get myself in a position to be successful.”

It was a satisfying conclusion to tough start with the win-now Nationals, who named Treinen the closer at the end of 2017 spring training but moved on when two bad outings in succession bumped his ERA into the nines.

His 5.73 ERA at the time of the trade had dropped to 3.93 by the end of the season.

“You learn from it,” Treinen said. “This is a business, and if you have any slip-ups things can change quickly. It’s in the past. It is nice to come out and have a team that has confidence in you.

“It’s a team in D.C. that needs to have results right away because it is a team that is built to win for the last decade. For someone to have to learn in that role, I don’t think it molds well. They need somebody experienced in that role. I don’t really want to dwell on the tough stuff, but it did shape me to continue to put my head down and work hard.”

Treinen, originally signed by the A’s in 2011, was traded to the Nationals in a three-team deal that brought John Jaso in 2013.

A starter early in his career, Washington converted him to the bullpen, and scouts have always believed his sinking fastball/slider repertoire played well there.

Treinen’s average fastball was 97.6 mph in 2017, according to Fangraphs, among the best in the league. Because of its sink, his ground ball to fly ball ratio was among the top 15 among relievers.

“It’s at a high velocity and it is moving quite a bit,” Melvin said. “There are very few guys that have the kind of ‘velo’ and movement.

“The stuff has always been there. I think the change of scenery from Washington to us kind of gave him a new breath and he performed really well for us. There is no reason for us make any change in that role.”

Petit and Buchter will add to a bullpen that includes veterans Santiago Casilla and Liam Hendricks, among others. Buchter is the lone lefty.

Petit, a rookie spot starter on Arizona’s 2007 NL West title team managed by Melvin, has developed into a reliever capable of wearing many hats. He had a career-low 2.76 ERA in a career-high 60 appearances with the Angels last season.

“He is probably as versatile a pitcher as there is in the game,” Melvin said. “If ever there is a fix-it-all (guy) and a guy that can pitch in any inning and doesn’t make any excuses about where he pitches, just wants to perform for the team, it’s him.”