Jordan Zimmermann’s struggles to hold baserunners did not escape Matt Williams’s attention Sunday. (Brad Barr/USA TODAY Sports)

The Nationals entered spring training under new Manager Matt Williams with a goal to limit opponents’ stolen bases. It’s been a work in progress. Through 20 games, the Nationals have allowed 18 stolen bases to opposing baserunners in 23 attempts. Last season, the Nationals allowed the highest percentage of stolen bases (83 percent, 95 in 115 attempts) in the majors.

During Sunday’s 2-1 split-squad loss to the Detroit Tigers in Lakeland, the Nationals allowed six stolen bases. Left-handed reliever Michael Gonzalez allowed former Nationals infielder Steve Lombardozzi to steal on him twice. The Tigers speedier runners, Rajai Davis and Ian Kinsler, executed a double steal on Jordan Zimmermann in the first inning. The Tigers stole again on him the next inning. Williams said Zimmermann tried to vary his time on the mound to throw off the runners, but Gonzalez needs to improve.

“That’s atypical of the way we want to go about doing it,” Williams said. “He’s got to hold baserunners a little bit better than that. … We’re preaching that in spring training, the fact that we need to do a better job of holding those guys.”

“We just gotta do a better job of keeping an eye on them over there,” Zimmermann said. “We’ve all been working pretty hard this spring at varying our looks, holding and stepping off. But ultimately, we’ve got to give the catcher a good quality throw and something they can handle.”

During the double steal, Zimmermann fired a slider in the dirt, so it was a difficult pitch for catcher Jose Lobaton to get off a throw. In the second inning, Zimmermann varied his times, but the moment he didn’t look at Bryan Holaday, the runner stole third base. Lobaton threw to third but Holaday slid in safely. Last season, opposing runners stole 14 bases on Zimmermann in 19 attempts. Zimmermann said he wasn’t concerned about the stolen bases allowed but is working to improve.

“We just gotta do a better job of keeping an eye on them over there,” he said. “We’ve all been working pretty hard this spring at varying our looks, holding and stepping off. But ultimately we’ve got to give the catcher a good quality throw and something they can handle.”

Zimmermann fired four solid innings, allowing one run on four hits and struck out three despite shaky command. He hit Kinsler in the arm in the first inning. Gonzalez, who was making his second spring training game appearance, allowed a run on two hits and walked a batter. Lombardozzi led off the inning with a single and stole two bases, setting up the run.

“He’s been around the block a time or two and he understands that he is fairly slow to the plate and he needs to vary his times and his looks and things like that,” Williams said.

Lobaton has allowed eight stolen bases and thrown out none, while starting catcher Wilson Ramos has thrown out two and allowed only one stole base. Williams, however, said Lobaton is throwing the ball well and the pitchers are ultimately responsible. “We have to give our catchers a chance,” he said.

>>> The Nationals tested the new instant replay system for the second time this spring. In the seventh inning, with Xavier Cedeno on the mound, Ezequiel Carrera singled to left field. Bryce Harper threw behind Carrera and tried to catch him off the base after a wide turn. It was a close play but even Williams knew it wasn’t an out.

But he still emerged from the dugout to tell the first base umpire that he wanted to challenge the play. There was an eight-second delay on the television feed — Williams said it will be instant during the season — so to buy time he told Lobaton to go to the mound. Two umpires went to the replay booth near the visitor’s dugout. After a minute or so, they signaled that Carrera was indeed safe and the play stands. The entire replay review took less than two minutes.

“It’s just a question of going through it any chance we get,” Williams said. “I didn’t think that we got the guys on any of the other ones either, the stolen base at third. But at some point during the game, you have to practice and we want to work that process as much as we can. It wouldn’t be right for us to go through a whole game and not use one if there was something close that we could use it on. During the season, it’ll be a lot quicker. We’ll have instantaneous feedback.”

>>> Right-handed starter Doug Fister, who hasn’t pitched in a game on March 2 because of elbow inflammation, will pitch in a minor league game on Monday, Williams said. Fister will throw about 30 pitches, to simulate two innings, and Ramos is expected catch him. Fister, who threw a bullpen session on Friday, played catch Sunday.

>>> In the bottom of the seventh, Harper tried to bunt to get on base. Reliever Phil Coke fielded the ball and threw Harper out, but Williams thought it was a fine attempt. Coke falls hard to the third base side of the mound and is a left-hander, so it is a tough play. A school of thought in baseball would cringe at a power hitter like Harper, who is also good at drawing walks, dropping down a bunt. But Harper has speed and Williams leaves the decision to bunt for a hit up to the outfielder.

“Depends on the situation, depends on what we got,” Williams said. “If we’ve got a man at third and we need a run, it’s an option for him. And it’s an option for him at any time. To have that in his arsenal that’s good. Doesn’t mean he has to do it all the time.”

>>> Left-hander Sammy Solis made his second appearance of the spring after missing some time with back spasms. He fired two scoreless innings, walked one batter and didn’t allow a hit.

>>> Sunday was the first day a Nationals pitcher batted for himself this spring. Williams told Zimmermann before the game that he wanted them to bunt no matter the situation. Even with the bases loaded  — he wanted them to practice bunts. So when Zimmermann came up to bat with two outs in the third inning, he was in an awkward yet humorous position against Justin Verlander.

“I walked up there and told the catcher, ‘Just throw it over the middle, I’m just trying to get a bunt down,'” Zimmermann said. “I don’t know if he believed me or not. Then Verlander threw it. He said, ‘Two outs, right?’ ‘Right over the middle is fine.’”

Zimmermann said he was even heckled by some fans in the stands for not swinging. He bunted anyway and Verlander threw him out at first.