Archie Bradley’s Peculiar Debut

Let’s follow a tried-and-true format, unimaginative as it is. I’ll throw in a twist. There’s the imaginative part.

The good! Archie Bradley, so far, has made two starts in the major leagues. He’s faced maybe the best team in baseball, and last year’s World Series champion. He’s allowed a total of five hits and two runs, leaving his first start with his team ahead of Clayton Kershaw, and leaving his second start with his team ahead of Madison Bumgarner. His team also isn’t very good, so there are some bonus points.

The bad! Bradley’s come up just a hair shy of 60% strikes. He’s paired 10 strikeouts with six walks, so the command issues that’ve always been there haven’t disappeared. To this point, he’s lived almost exclusively fastball-curveball.

The ugly interesting! Bradley’s basically tied for the league lead in groundball rate. Of the 31 pitches batters have hit somewhere fair, they’ve put 23 of them on the ground. He hasn’t faced extreme groundball-hitting opponents, and he doesn’t have a ground-balling track record, and this is one of those things that’s supposed to sort itself out in a hurry. Groundball pitchers generally get grounders every time out. Fly ball pitchers generally put the ball in the air every time out. There are exceptions, odd reversals, but the probability gets lower when you consider back-to-back starts. Already, we might start to think of Archie Bradley as a groundball pitcher. With the weird thing being, he hasn’t been one, and he probably shouldn’t be one.

First, let’s quickly examine Bradley’s history. In 2012, in Single-A, Bradley put in his first full professional season. He generated groundballs just over half the time, which is a fairly groundball-y thing to do. But! In 2013, Bradley made his way to Double-A, and on the year, he wound up with 41% groundballs. The next season — so, last season — Bradley saw Triple-A, and between levels, he generated 42% groundballs. Nothing here to indicate strong groundball tendencies. The vibe you get is that Bradley was a prospect who lived more or less up in the zone with his big fastball.

So this year, in the majors, Bradley has allowed just 31 hit balls, fair. That is a small sample, but don’t let that be the takeaway. Let’s go with some simple math, in the form of binomial probability. Bradley’s career minor-league groundball rate is just under 46%. What are the odds that a 46% groundball pitcher would generate 23 or more groundballs out of 31 opportunities? Your answer:

• 0.114%

On its own, that doesn’t tell you much of anything. That just says, hey, this is unlikely, given the initial conditions. Makes you think something else is going on. Could be, in part, something flukey. Could be, in part, up to the opponents. But then you think about those initial conditions. Maybe we got the initial probability of a groundball wrong, because Bradley isn’t what he has been. Maybe he’s adopting a different approach.

Unfortunately, one thing we don’t have is a bunch of pitch-by-pitch minor-league data for Bradley. But we can just examine the major-league stuff for clues. And here’s a strong one: so far, about 52% of big-league fastballs have been thrown somewhere in the lower half. In other words, if you look at the vertical middle of the strike zone, just over half of all fastballs have been located somewhere below that line. That’s for all teams. Archie Bradley comes in with an individual rate of 72%. The top five in baseball, in the early going, with a 100-fastball minimum:

1. Sam Dyson, 79.5%
2. Jerome Williams, 79.0%
3. Roberto Hernandez, 78.6%
4. Mike Leake, 72.4%
5. Archie Bradley, 72.3%

Bradley’s thrown his fastball low. That’s the point. Almost three out of four of them below the vertical halfway line. Here’s Bradley beginning three consecutive plate appearances against Buster Posey, last week:

Pretty low fastball, pretty low fastball, pretty low fastball. Posey did manage to put one of them in the air, but, that can happen. And an important note is that Bradley doesn’t appear to be throwing a sinker. His fastball movement is more like that of a four-seamer, but he’s mostly used it like a sinker. And this might be an organizational thing. A year ago, the Diamondbacks’ pitching staff ranked No. 1 in baseball in rate of fastballs thrown low. The Diamondbacks themselves have seen a lot of changes from 2014 to 2015, but this year, that rate has hardly budged. It’s a low-working group of pitchers.

Let’s get back into the movement stuff, though. It’s not uncommon to see pitchers who throw low in the zone. It’s actually extremely common. But those pitchers, generally, have sinking fastballs. Bradley’s fastball is designated as a four-seamer, and it actually has even less sink than the average four-seamer. Last season’s average four-seamer for a starting pitcher had a vertical PITCHf/x reading of 9.2. Bradley this year is at 10.0, meaning he’s had about an inch more rise.

As an experiment, I ran through my pitch-comp methodology for Bradley, comparing his 2015 fastball to 2014 four-seam fastballs thrown by starting pitchers. I set a minimum of 200 thrown, and I found the closest comparisons to Bradley’s four-seamer based on velocity, horizontal movement, and vertical movement. There were 21 different four-seam fastballs that showed up with a comp rating no greater than 1.0. These are what I consider to be strong comparisons.

The next step: find out what those pitchers did with those four-seam fastballs. Using Brooks Baseball, I found the average pitch height, in feet, relative to the vertical center of the zone. Below, a table, of pitchers from 2014, and Bradley from 2015. They’re listed in descending order of pitch height, going from the highest average four-seamer to the lowest average four-seamer.

Second from the bottom: 2015 Archie Bradley. The only guy lower: a 2014 Diamondback. There’s a pretty big gap, relatively speaking, between Bradley and the next guy above him, meaning that Bradley’s average four-seamer has been unusually low, compared to guys with similar four-seamers. The average for the non-Bradley pitchers is 0.08. Bradley is lower by 0.4, or almost five inches. Just to make that as clear as possible: compared to starters with similar fastballs, Bradley’s average fastball this season has been lower by five inches, which is significant.

That group, also, had an average groundball rate of 42%. Kyle Gibson had the highest, but then, he threw his sinker more than twice as often as he threw his four-seamer. Brandon McCarthy was next, but he threw his sinker more than three times as often as he threw his four-seamer. And then there’s Wade Miley, the only other guy in the group with a groundball rate of at least 50%, but according to Brooks he evenly split between four-seamers and sinkers. Bradley doesn’t really seem to throw a sinker. Based on his comparisons, he shouldn’t be a groundball pitcher. But he’s also using his fastball differently from the others, so it shouldn’t be a complete surprise he’s getting different early results.

It all makes you wonder. Based on his history, Bradley has thrown more fastballs upstairs. Pitchers like Bradley throw more fastballs upstairs. The one exception has been a pitcher from the same team a year before, which makes you think this could be an Arizona thing. But Bradley’s worked low, which is probably deliberate. And it seems to signal an altered approach, as Bradley has long been considered a work in progress. So, is this just what he’s going to be? If so, he stands to be unusual. He’d stand to miss fewer bats than he would otherwise, but maybe Bradley can stay around the zone more if he focuses on the bottom half. And that’s been the real problem for him. Maybe he’s just going to be a groundball pitcher now despite throwing a riding four-seamer. Didn’t look like that would be the case, but then, he was never really a finished product, now, was he?