How the knee-down revolution changed catching - without downgrading defense

Swanson initially thought that having a knee down might affect how umpires perceived pitches: Since umpires typically position themselves between the batter and the catcher’s inside shoulder, Swanson experimented with dropping the right knee for a left-handed batter and the left knee for a right-handed batter.

“I thought there was a chance umpires were using the catcher’s body, specifically their knees, to gauge the height of pitches,” he said. “I thought if we remove the knee from their visual field, maybe they’ll lose perception. … I was never able to validate the hypothesis.”

However, he found there were other benefits to catchers being closer to the ground: The best framers got most of their borderline strike calls in the lower portions of the zone. Moving the glove up to catch a ball at the bottom of the zone made it seem like the glove finished in the zone.

In 2017, among pitches taken by hitters in borderline areas - the “shadow zone,” as Baseball Savant defines it - 48.4% were called strikes with no runners on base, but the strike rate dropped to 45.1% with runners on, when catchers used higher, wider stances.

That data made a compelling enough argument to adopt a lower stance on all pitches, regardless of whether there were baserunners.

Caught stealing above average stat breakdown

This stuff is fantastic. Hopefully, they plan on expanding such breakdowns to other positions. We already know who has the strongest arms. Anyone who has ever played knows it’s not just the arm strength. So who is the most accurate? Who combines both?

The same is true in the infield. How much impact does a great receiving 1B have? Who is the best at scooping throws?

Now, I imagine the impact isn’t great but finding out who is good at these skills is still helpful as I have found that incremental improvements in a lot of areas add up. It also might help us better appreciate a good 1B playing in front of a scatter-armed infield.

So Smith, currently sidelined as he works his way back from concussion symptoms, looks like he’s a pretty poor preventer of stolen bases, having cut down just one of the eight basestealers he’s seen, an unimpressive 11% rate that’s less than half of the 25% mark he had two seasons ago. (It’s actually worse than that: He hasn’t thrown out anyone, but instead got credit when Julio Urías picked off Mike Yastrzemski.)

Except … wait a minute. We know Syndergaard is extremely poor at holding runners on; he’s talked about this, openly, for years, and last year, 30 of 33 basestealers were successful against him. We know that Carroll isn’t just “very fast,” he is “literally the fastest.” Maybe it’s not so much that Smith didn’t do his job. Maybe it’s that the job he was given wasn’t possible to do.

Maybe, as 2013 NL stolen-base champion Eric Young Jr. once said, echoing the thoughts of a century’s worth of backstops, “You’re usually always stealing off the pitcher. Catchers … you know it doesn’t matter if he has a good arm. If you get a good jump off the pitcher, the catcher’s not going to be able to catch up.”