Eduardo Rodriguez’s ever-evolving arsenal

I’ve always been something close to the low man on Eduardo Rodriguez, which I’m sure I’ve mentioned before but am too lazy to double-check. I thought he was fine during his rookie year and while I was confident he could carve out a role as a major leaguer, I wasn’t as convinced as many he had the potential to take the next step as a near-to-of-the-rotation type.

The start to his 2016 didn’t give me much more confidence, and he was bad enough that he was eventually sent back to Triple-A after starting the year on the disabled list. It looked like the start of a lost year for Rodriguez. The team obviously still has confidence in him, though. Dave Dombrowski had every chance to get more rotation insurance last week — the prices for starters obviously had something to do with this as well — but they declined. Instead, they’ll continue to give Rodriguez the ball every five days during a playoff run.

Well, since the 23 year old has returned from Pawtucket in mid-July, he has made the team look smart and me look dumb. Shocking development, I know. He’s up to four starts in that stretch, which is still a small sample but is rapidly growing. (Duh, that’s how linear samples work.) Rodriguez has thrown 24 innings in that stretch (six frames per start, for the mathematically challenged), with an impressive 2.63 ERA. To go with that, he’s carried a 21 percent strikeout rate and an eight percent walk rate and has limited opponents to a .703 OPS. None of that is mind blowing, of course, but it’s a huge jump forward from where he was even just six weeks ago. Plus, there’s been one tangible change in his game since then.

If you’ve been paying any sort of attention to the team during this stretch, you know that I’m referring to the lefty’s recommitment to the slider. It was something that was almost completely absent during his initial major-league stint this year, and the numbers reflected the lack of change. He’s gone from throwing in a little over four percent of the time before his demotion to a little over 30 percent of the time post-promotion. It’s not simply skewed by one outing with a high slider-usage, either, as can happen with samples this small. Rodriguez has stuck with a steady 25-35 percentage usage rate on the pitch in each of his four outings.

The rediscovery of the breaking ball isn’t the only reason for his sudden ascension, of course. Things are never that simple. With that being said, it’s pretty clearly been a driving force. Rodriguez isn’t just throwing the pitch more frequently, but he’s getting strong results from it as well. The pitch is inducing whiffs on 36 percent of swings, and while it’s allowing line drives on a third of the balls in play, it’s also inducing infield pop ups on a third of fly balls. As we know, a pop up is almost as good as a strikeout. Even better, he hasn’t allowed a home run with the pitch since coming back. For a pitcher who has had a relatively hard time racking up high strikeout totals in his career, bringing back this kind of whiff-inducing pitch is huge.

Of course, for every action there is an equal and opposite reaction, and this physical truth also extends into Rodriguez’s 2016. As he’s brought back the slider, he’s also started to cut way back on his changeup usage. To wit, he’s gone from throwing it roughly 20 percent of the time pre-demotion to under 10 percent of the time post-promotion.

Clearly, this adjustment has worked so far. Just scroll up a bit and look at those numbers. 2.63 ERA! That’s good! In fact, there’s an argument to be made that this was a smart move for the long term. The changeup hasn’t really worked well for him this year. Before his demotion, he was getting a good number of whiffs with the offspeed offering (32 percent), but when he wasn’t getting whiffs, he was getting crushed. Just over 30 percent of the balls in play he was allowing were registered as ground balls, and 27 percent of the balls hit in the air left the yard.

With that being said, he needs to figure out how to get his slider and changeup working to some extent at the same time. The latter hasn’t always been a failure, as it was a solid pitch for him last year. Right now, the re-emergence of the slider has been plenty, but it’s hard to bet on that to continue.

As you may know, major-league lineups are good at what they do. Even the worst lineups in the majors are super good at hitting. On top of that, major league coaches and scouting staffs thrive on making adjustments. That’s why pitchers don’t last long as starters in this league with just two pitches. Rodriguez’s recent run is more encouraging than not, and it’s given his profile a much-needed boost. If he’s going to continue to be a factor for this team as it tries to reach the postseason, though, he’s going to need to work his slider and changeup successfully into his arsenal at the same time.