Mixed Results for D-backs’ Sinker Experiments

The D-backs staff’s ground ball percentage has tailed off a bit from where it was earlier this season, but it’s still up there — 46.1%, ranked 12th — and that’s still some kind of small shock, considering it entered the season with a staff of fly ball pitchers. A huge part of that is the relentlessness with which they’ve pitched down in the zone, but for Rubby De La Rosa, Chase Anderson, Jeremy Hellickson and Robbie Ray, part of it is repertoire: the sinker. Either way, most saw their ground ball to fly ball ratio (GB/FB) rise this season:

*minor league ratio, from mlbfarm.com                            †2013 ratio

Other than that: RDLR, Anderson, Hellickson, and Bradley all raised their GB/FB ratios — and all did worse than expected by ZiPS. Ray has decreased his GB/FB ratio, and he’s done significantly better. Patrick Corbin’s ratio is up, but he’s done better; the only other exception is Collmenter, who is kind of an odd case. Collmenter was already an especially ground ball version of himself as a starter in 2014, using a curveball and trying to stay in games later. Since returning to the bullpen this season, he’s thrown 44.2 innings, his GB/FB ratio back down to 0.74. Oh, and a 1.61 ERA.

That’s me burying the lede without burying the lede. As kind of a general rule, the more a starter increased his GB/FB ratio, the worse he’s done. That’s not all sinker, but check this out:

Corbin’s thrown his sinker less; and he was one of those guys who’s done better than expected (Collmenter will stick with his cutter, thank you). RDLR went way up, and he’s done worse (as we saw on Monday, that’s mostly a matter of the sinker getting punished by lefties). As for Anderson and Hellickson — these year-long numbers might not tell the whole story.

Anderson has pitched just 7 innings in September, Hellickson just the one — so let’s not get hung up on those numbers. In the season’s other five months, Anderson’s top sinker month (July) corresponds with his worst performance; Hellickson’s isn’t necessarily a month-to-month match. Anyway, on to the sinker results.

***

Robbie Ray: GOOD

Robbie Ray keeps throwing his sinker more and more; last year and in his first spot start in May, he threw none. When he came back up in June, he threw it 10.12% of the time, which rose to 18.15%, then 23.08%, then 27.23% so far this month. It’s not hard to see why he might want to.

It looks from these foul percentages like Ray is very hard to square up; it looks from the whiff percentages that although hitters have a hard time squaring up the ball, when they miss, they don’t miss over or under it (or early or late). This is not breaking news, but I’ll still renew the call for Ray to try a hard, thrown-like-a-fastball Dan Warthen slider. It would be nice if Ray could make hitters miss completely a bit more often without the high home run risk presented by his hangerball (which also has a high line drive rate).

That said: the sinker experiment worked, here. Astonishingly well. A 3.89 GB/FB rate is positively ridiculous (last year, Brad Ziegler‘s GB/FB was 3.38, although this year he’s picked ground balls over strikeouts). He’s thrown it 326 times, and yielded a home run just once. It’s a contact pitch, and it does get called for a ball much more than his four-seam (for RHH, in particular, the sinker can both look and actually be unreachable at times). It’s not a substitute for a breaking ball as the foul rates show, but yes — it’s part of Ray’s success this year, and he should stick with it.

Rubby De La Rosa: GOOD AND BAD

I’ll refer you back to Monday, where we saw: the sinker is complete garbage against left handed hitters, but looks very promising against RHH. So that’s a partial victory for the experiment, as he may never have really tried it against RHH otherwise.

Jeremy Hellickson: GOOD, BUT

Hellickson hasn’t really been throwing the pitch more, and when he has, he’s arguably done better; best on the graph above, when Hellickson brought the pitch back in late summer, it may have helped him get on a roll.

This may be because of his dedication to pitching down, but here’s the rub: hitters don’t swing at it so much (40.2%), and partly as a result, it gets called for a ball very often, even in contrast to his other pitches (overall, his strike rate is not very high). So it’s almost like: of course the results are great on the pitch. It’s part “what are batters’ results on all balls thrown outside the zone.”

For Hellickson, we may be monitoring the down-in-the-zone thing much more than his sinker usage. In fact, these sinker numbers might be a reason not to pitch so exclusively down in the zone; if your four-seam is at the knees, the sinker may not work unless you make it look like it’s headed for the same spot (only to sink below the zone). So Hellickson’s sinker is all good, but it wasn’t necessarily an experiment, and the results may be clouded from the team’s other experiment, the pitching down one.

Chase Anderson: ¯\_(ツ)_/¯

The idea of an increased ground ball rate seemed to be to take advantage of the D-backs’ elite defense at short and around the infield, and to cut down on home runs. By the time Anderson backed off the pitch in July, the home run rate on it was 1.3%, with an even greater difference between pitches. Sinkers actually hit in play (exclusive of balls hit over the fence) fared quite a bit better than his other fastballs. By both yardsticks, the sinker has failed to help.

All we’ve really learned, though, is that it’s unlikely to be as helpful as hoped. In terms of using this year’s data to inform next year’s decisions: what can he really do differently? He can’t really throw the curve or change more often, so the replacements for sinkers would mostly be four-seam fastballs — and while that looks like a good thing based on this year, in 2014 opponents had a .366 BABIP on Anderson’s four-seam.

***

The true results for these pitchers’ sinkers probably rest somewhere between their overall results when using it and their results specifically on that pitch. Anderson’s results on his four-seam fastball are poor, but they probably help his changeup dominate, and we can’t just insist he throw his change as if it were his fastball. It’s possible that these guys’ sinkers helped make other pitches more effective. On the whole, though — it certainly looks like more sinkers has been a good thing.