The new Twins front office began the process of improving the pitching staff by signing a catcher Tuesday.

Jason Castro, who played six seasons for Houston, is considered one of baseball's best pitch-framing catchers, and his value to the Twins was worth a three-year contract worth $24.5 million.

But what is pitch framing and why is it valuable?

A 2014 ESPN exposé described catcher framing as "an act of subtlety, receiving the ball close to the chest, never stabbing at it, and turning pitches that nick the border of the zone — or at least appear to — into called strikes."

The article further explains: "Though framing is an almost indiscernible art form, it is now quantifiable. Baseball Prospectus has developed metrics that measure, in essence, the extent to which catchers are responsible for the calls that go their way. When you consider how many times a good framer influences at-bats, and how many runs that can save during the course of a season, you see how truly valuable he is to his team. Now that's a great catcher."

Buster Olney, ESPN's baseball insider, wrote that the top free-agent catcher on the market, Baltimore's Matt Wieters, might not be so valuable anymore because of his poor pitch-framing metrics and declining offensive production.

What makes Castro so great?

Castro had 96 more strikes called last season than what was expected, according to That was fifth-best among major league catchers. He also threw out 24 percent of runners attempting to steal bases last season.

The 6-3, 215-pound Castro was an American League All-Star when he batted .276 with 18 home runs and 56 RBI in 2013. He hit only .210 last season, but his value isn't in his bat.

Castro's defense and pitch-framing metrics are why he was being pursued by several teams offering at least a three-year deal.

In 2013, Houston began putting an emphasis on pitch framing, and it was reported that Castro was among the worst in the organization. However, during the past two seasons Castro has been credited with the way he caught 2015 American League Cy Young Award winner Dallas Keuchel and presented the lefthander's pitches "admirably."

How does Castro compare to out­going Twins catcher Kurt Suzuki?

Suzuki had 38 fewer strikes called last season than what was expected, among the worst in the league, according to Again, Castro's rating was plus-96.

Suzuki, a 2014 All-Star, threw out only 19 percent of runners attempting to steal last season.

Defensively, Castro appears to be a quality upgrade. And as Star Tribune Twins writer La Velle E. Neal III pointed out, if there is a position where it's acceptable to sacrifice offense for defense, it's at catcher.

Neal wrote this week: "Twins pitchers liked throwing to Suzuki and how he called games. But they should immediately benefit from Castro's moxie behind the plate. The staff's 5.08 ERA was the worst in the American League, better only than Arizona's 5.09."