Since Joe Mauer hung up his mask three years ago, no major league team’s catching corps has thrown out fewer baserunners than the Twins’. They have finished last in the American League in all three seasons, and last in the majors for the past two.

So it’s no wonder Jason Castro was such a popular face at TwinsFest this past weekend.

“It’s been great. The fans have been really supportive,” Castro said of his first interaction with Minnesotans. “A lot of curious looks — ‘Who’s that guy?’ There’s a little bit of curiosity [about] the new side of catching and what that entails.”

The Twins are curious, too, especially given Castro’s reputation (and statistical résumé) for pitch framing, the art and science of subtly influencing an umpire’s ball-and-strike calls in the pitcher’s favor. Castro spent the first six years of his MLB career with the Astros, an organization that has prioritized pitch framing, and he’s a believer — as are the Twins’ new front-office leaders — in the impact that just a few additional strikes can have on a pitcher’s performance.

“We’ve said several times that improving our pitching performance is a fundamental priority, and by adding a catcher who is a leader, who brings a solid base of defense and who can do things that help the pitcher at critical moments of a game, we feel that, in effect, we can impact the success of each of our pitchers at once,” Derek Falvey, the Twins chief baseball officer, said of his first free-agent signing in his new role. “We know that [working] the count in the pitcher’s favor can have a huge impact on an at-bat. The difference between a 2-1 count and a 1-2 count can be enormous. … Jason has a track record of helping some quality pitchers fulfill their [promise].”

By some metrics, he saved Astros pitchers more than three dozen runs last season, while Kurt Suzuki cost the Twins staff more than two dozen. That sort of impact was worth $8 million a year to the Twins.

Castro has been studying video of each of the Twins pitchers since signing a three-year contract in November, and he spent this weekend at Target Field getting to know them personally.

“Just getting on the same page, so we know how we’re going to start out when we get to spring training,” Castro said. “Catching is a little different. There’s a little more of a selfless side to it. You have a big responsibility to the pitching staff — they expect you to have their best interests at heart and have [done] the preparation so they can trust you.”

He’s not just critical to the Twins’ plans to improve their pitching staff, though. Castro is also central to bench coach Joe Vavra’s new responsibility: corralling the running game.

“Jason is known as a good defensive catcher, and that’s been a frustrating area for us,” Vavra said. “Particularly last year, [stopping] the running game has been a weakness that is making life more difficult for the pitchers. Some of the young guys, they feel if they pay too much attention to holding runners, to being quicker to the plate, they’re prone to give up homers. So they’re not able to separate the two.”

Castro should help. In Suzuki’s three seasons with the Twins, he threw out only 26 runners trying to steal (and just seven in 2016), while allowing 196 stolen bases. In those same three seasons, and in 1,250 fewer innings behind the plate, Castro has thrown out 54 runners, more than twice as many.

Pitch framing may help there, too. If Castro can help pitchers get ahead in the count, stolen base attempts could decline.

“He’s got a little niche at that, and he works hard at it,” Vavra said. “When the catcher can make it more convincing for the umpire, he’s going to get more calls for his pitcher, and more strikes. We need to be pitching ahead more.”