A funny thing happened at the start of the season: even though the rotation was to be manned by three fly ball pitchers, by the end of April the D-backs staff was fourth in the majors in ground ball percentage at 49.1%. It wasn’t all Brad Ziegler. Archie Bradley was a big part of the sharp change in the staff’s batted ball profile, but all four rotation members saw their ground ball percentage tick at least somewhat upward. It seemed like it might have been part of a plan.

With Bradley’s DL stints, he’s had a lot less of an effect on the staff GB% since then. In May, the D-backs’ rank in GB% plummeted from 4th to a tie for 15th — exactly middle of the road, at 45.4%. That’s a pretty enormous change. So far in June, the team has ticked back upward a bit — to 46.1%, good for 14th in baseball. And yet, there may be more to it than that.

Home runs have been an issue for this staff, and they may always be a problem for a team that plays more than half of its games at Chase Field and Coors Field. That’s probably the biggest danger of a high fly ball percentage — unless a pitcher is an extreme fly ball pitcher, having a mark above average generally means yielding more home runs. Sure enough, D-backs pitchers are ranked 5th in baseball so far with 67 home runs allowed. D-backs pitchers have been responsible for just 64 games. Could be worse. A year ago today, the D-backs had already given up 86 home runs; the season started a bit earlier, but it’s a difference of only four games.

So why hasn’t it been worse? The D-backs staff ranks 23rd in ERA, with only the Rockies trailing them in the NL.

2014 GB% 2015 GB%
Rubby De La Rosa 45.7% 48.7%
Chase Anderson 39.9% 45.5%
Jeremy Hellickson 36.5% 44.2%
Josh Collmenter 38.8% 33.9%
Archie Bradley 50.2%* 58.0%
Andrew Chafin 62.3%* 60.4%
Randall Delgado 35.2% 45.8%

* According to mlbfarm.com batted ball data for time in the minors

These are the seven pitchers who lead the D-backs staff in innings pitched — and all but 2 have seen a rise in ground ball percentage this year of at least three points. Averaging the seven together, that’s an increase of 4 percentage points — the kind of thing that doesn’t really happen by accident.

Robbie Ray is a fly ball pitcher, and there’s no getting around that. With his arm angle, asking him to regularly pitch down to his glove side might be the equivalent of sending embossed invitations for extra base hits. In addition, his fly ball percentage isn’t just high — it’s extremely high, maybe so much so that he’s passed the danger zone and into a happy area where he’s been able to make up for extra home runs with extra “no such thing as a sure out but these come damned close” popups. Ray tallied a ridiculous 44 popups last season in less than 130 innings, nearly 10% of all balls hit in play (seriously!). Ray is okay being just who he is.

But consider the other decisions made by the team. Josh Collmenter is out of the rotation — he also had a ground ball percentage that he could start to qualify as an extreme fly baller, but he managed a good-not-great total of 13 popups this season in his 68.2 innings. Collmenter also managed an identical pretty-close-to-putrid total of home runs. He was not okay being just who he was. He did not make a significant ground ball advancement like almost everyone on the staff. He is no longer being counted on to pitch as many innings.

Of the seven pitchers above, the only one other than Collmenter to have seen a decreased in GB% is Andrew Chafin — and 60% is a pretty hard thing to achieve as it is, unless you’re Brad Ziegler. Based on the team’s actions and these numbers, it’s hard to escape the idea that ground balls have been a priority for the D-backs. This bears all the badges of being on purpose.

Part of it is pitch selection. Chase Anderson may be the poster child for this movement, and in spring training, he announced that he was going to try to get away from his four-seam fastball more frequently, relying more on his sinker. At the time, we thought more sinkers was a stupendous idea (and before then, as well). We haven’t quite seen that kind of commitment, but Anderson has stepped up his sinker usage a bit, from 21.2% last year to 23.3% this year. He’s also finally thrown his changeup more than 20% of the time, from 19.8% to 22.2%. He hasn’t actually thrown the four-seam less, but taking something of a step back from his curveball seems to be working wonders. The slugging percentage against each four of his pitches has improved this season.

He’s not the only one. Rubby De La Rosa recently stepped things up in terms of throwing sinkers, maybe in part because he was required to throw what Welington Castillo called. Allen Webster showed up on throwing a heaping helping of sinkers, which is not something we’ve seen in the majors before (more on the RDLR and Webster points here).

It’s not just about pitch selection, though. After we noticed an uptick in sinkers in spring training, we warned that despite the likely need to cover a boatload of innings as a long reliever, it did not make sense for Randall Delgado to return to throwing his sinker as a reliever. His ground ball percentage has jumped more than ten points, and yet he’s thrown his sinker just 11.8% of the time — much closer to his experience as a reliever last year (9.9%) than to his year in the D-backs rotation in 2013 (54.1%).

Delgado is doing it by pitching down. Delgado has thrown 15.8%% of his pitches in the bottom third of the zone, not as small a change as last year’s percentage (13.6%) might lead you to believe. Jeremy Hellickson is in the same camp; he’s thrown 18.4% of pitches in the bottom third this year, after a 14.6% the year before.

In April, it looked like Nick Ahmed might be connected to the uptick in ground ball percentage, and I think he probably was, and has been all season. Despite a rocky first week in the field, Ahmed has been nothing short of stellar out there. In Defensive Runs Saved, Nick Ahmed’s 11 trails only Andrelton Simmons (12), and he’s way ahead of the next shortstop on the list (Zack Cozart, 7). Ahmed also ranks second in Ultimate Zone Rating, 6.6 to Jose Iglesias‘s 7.3 and ahead of Simmons (5.6). The man is the real deal, and he is eating up what the D-backs are serving.

But maybe he’s not the only reason. Remember how the team saw its GB% dip in a big way in May this season, after a very high showing in April? This recent uptick may have something else in common: America’s Third Baseman to Be, Jake Lamb, who did not start a game between April 18th and June 7th. This coincides almost perfectly. The team tried to start the season with a Lamb-Ahmed-Owings-Goldy infield, which promised to be one of the game’s best, defensively. That alignment is possible again now, and it looks like the team is taking advantage again. So buckle in, folks — these baseballs are in for a bumpy ride, and while the staff is not doing very well overall, they’re doing something very important in a great way.

One Response to D-backs Pitching Staff Prioritizing Ground Balls Again?

  1. […] By that point, Rubby De La Rosa, Chase Anderson, Jeremy Hellickson, Randall Delgado and Bradley had all raised their GB% substantially. That doesn’t mean it was working, by the way; a big part of that was pitching down in the […]

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