The emergence of Eduardo Rodriguez’ cutter

The Red Sox have gone through a middling stretch of late, and whether you think it’s worrisome for the long-term or not the one thing we should all be able to agree with is that the rotation is not the issue. Boston’s starters have been outstanding, really all year but especially lately (Friday notwithstanding). This group has been putting quality start together after quality start, and as a result the Red Sox at least have a chance in every game. Every starter has played a role in this, but today I want to talk about Eduardo Rodriguez. This shouldn’t surprise people, both because his name is in the headline and also because I love writing about Rodriguez. Recently, I wrote about his frustrations and moving past those. A lot of the inefficiency issues still exist and it’s something for him to work on, but despite that he’s been really, really good in 2018. There are many reasons for this, but it seems to me that the biggest change for Rodriguez has been the added focus on his cutter.

Before we get into the young lefty’s pitch selection, let’s take a quick moment to appreciate how well he’s pitched this season. After starting the season with a brief stint on the disabled list, Rodriguez has made 14 starts this season. In that time, he’s tossed 77 ²⁄₃ innings (about 5 ²⁄₃ innings per start) and has pitched to a 3.59 ERA (16 percent better than league-average), a 3.49 FIP (14 percent better than league-average) and a 3.08 DRA (30 percent league-average). Since May 10 — and keep this date in mind for a little bit later — Rodriguez has made eight starts and has not allowed more than three runs in any of them. He’s only allowed that many in one of those starts, and he’s allowed one or zero runs in three of them. The dude is on a roll, and the Red Sox are winning just about every game he starts (13 of 14 this year).

So, yeah, efficiency or no, Rodriguez has seemingly taken a step forward this year. As I said at the top, if you’re looking for one change that has dictated his success I would argue that it comes down to the lefty’s use of his cut fastball. If you’ve been reading this site for the last few years, you probably know why I think this is so important. Basically through Rodriguez’ entire career, my biggest issue with the lefty is that he’s never been able to fully trust his secondaries, leading to a lot of fastballs. He has a good enough fastball that he can get by with that approach, but it holds him back from taking the next step. This season, he has trusted his cutter on a consistent basis, and it’s changing everything.

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For what it’s worth, the classification of the cutter for sites like Brooks Baseball — the site from which the data in the rest of this post will come — can be tough. The movement on the pitch can be similar to that of a slider, and sometimes pitch-tracking technology can conflate the two offerings. This seems to be the case for Rodriguez, as Brooks indicates that he never threw his cutter last season, but this post from Tim Britton of the Providence Journal last year suggests otherwise.

It seems that this is worth noting, but the data suggests his usage of the pitch has risen significantly, and the good ol’ eye test agrees with it as well. According to Brooks, he has thrown the pitch 15.5 percent of the time this year. His previous career-high had been 2.8 percent. Again, the data may not be 100 percent here, but this big of a jump is certainly notable. Rodriguez is clearly throwing the pitch more in 2018, and is clearly very confident in it.

In fact, if you dig a little deeper the confidence grew as the year went on. Remember that May 10 date I mentioned above? That was the start of this incredible run he is currently enjoying, and it correlates extremely well with the moment he seemingly gained real confidence in the cutter. Prior to that game, he had a few outings in which he featured the pitch heavily, but there were others in which he never threw it. Starting on May 10, he has thrown his cutter at least 18 percent of the time in each of his starts, and more often it has been in the 23-25 percent range. As a result, he has been throwing fewer four-seam fastballs. After throwing his fastball at least half of the time in three of his first four outings this year, since May 10 he is maxing out around 40 percent. This is a massive development for the lefty.

Really, this entire trend is more about mixing his pitches than his cutter being some sort of dominant offering. The hard numbers, which you can see here if you’re interested, aren’t overly impressive. However, those numbers can often be misleading because the sequencing of an at bat has just as much — and probably more — of an effect on the end result of said at bat than the effectiveness of the final pitch. In this case, Rodriguez is becoming less predictable, and particularly with the cutter. He’s throwing the pitch just as often against lefties and righties.

The Red Sox rotation is on fire

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The best example of this lack of predictability can be seen with his usage of the cutter against lefties. There are two instances in which Rodriguez throws the pitch more than 20 percent of the time: When he falls behind, and when he gets two strikes. Those are, obviously, generally opposite situations, which shows real confidence in throwing the pitch whenever he wants. That’s long been missing from Rodriguez’ game.

Potential has always been the focus around Rodriguez, to the point where it can be hard to appreciate what he’s doing in the here and now. Fortunately, it seems as if he’s making the leap towards reaching that potential, at least judging by his numbers this year and particularly over the last month or so. These kinds of improvements rarely happen due to one change, and there’s probably more at play here as well. That being said, Rodriguez has always been on the search for a secondary in which he has consistent confidence. It seems he’s found it with his cutter, and it’s changing everything.