Brandon Woodruff Rebuilt Himself as a Starter

Brandon Woodruff did everything he could for the Brewers in 2017 and 2018. When the rotation needed reinforcements at the end of 2017, he started eight games. When the team needed relief arms in 2018, he filled whatever innings they needed — 10 of his 15 relief appearances went more than an inning, and he contributed four spot starts when the Brewers needed an occasional extra starter. This year, the team needs a starter again, and Woodruff has outdone himself. In 16 starts, he’s gone from solid bullpen arm to the best starter on a playoff team. If the team needs a pitcher to start an elimination game, Woodruff is probably the man for the job.

If I had been asked to make a prediction about Woodruff before the season, I think I would have landed somewhere near our Depth Charts projections — 23 starts, a 4.30 ERA and FIP, and peripherals that looked worse than his 2018 relief turn, when he struck out 26.7% of batters he faced and walked 8%. Pitchers who switch from relieving to starting tend to have worse rate stats across the board, and nothing about Woodruff screamed exception. Instead, he’s improved in essentially every category. He’s striking out 29.6% of the batters he faces, and walking only 6.5%. His FIP is 0.23 lower than it was last year. Heck, he’s gained fastball velocity, something you’re not supposed to do when throwing more pitches per game.

Luckily for the purposes of our analysis, however, he’s also made some changes in approach that we can pore over. If all there was to Woodruff’s improvement was a tick on his fastball, there wouldn’t be much to say. But that’s not how Brandon Woodruff’s season has gone. He has overhauled his arsenal and approach in ways that look well thought-out and sustainable to me.

First, take a look at Woodruff’s pitch mix change between 2018 and 2019:

The change jumps right out: Woodruff has gone from basically no two-seam fastballs to throwing them 20% of the time, subtracting more or less one-for-one from his four-seam. This move seems antithetical to the analytical, four-seam-and-curveball trend that progressive teams like the Brewers endorse. There are good reasons to switch to more two-seam fastballs, however, and Woodruff is a great example of why it makes sense.

For starters, one of the key benefits of a four-seam fastball is its ability to get swings and misses. That bat-missing prowess is why four-seam fastballs have become king even as contact is increasingly likely to result in home runs. There was just one problem — Woodruff’s four-seam wasn’t really a swing-and-miss pitch. That might surprise you — after all, he has above-average velocity and put up solid strikeout numbers last year. Despite the speed (an 80th percentile velocity among pitchers who threw 400 four-seamers last year), however, he was below average in terms of getting swings and misses with his fastball. Why is that? Well, not getting whiffs is always a complex combination of many factors, but one stands out: Woodruff was only in the 17th percentile when it came to four-seam spin rate. Given that spin rate scales with velocity, his fastball was one of the lowest-spin pitches relative to expectation in the game.

To make matters worse, Woodruff’s four-seamer didn’t pair naturally with his best secondary pitch, a hard slider with almost no depth. Why didn’t the slider pair well with the four-seam? It’s simple mathematics at its core — the slider doesn’t break far enough away from the four-seam on the axis Woodruff cares about. Without otherworldly ride on his fastball, Woodruff goes after batters horizontally, as you can see on this slider that he threw past Anthony Rendon:

Next, watch how well that pitch’s plane tracks with this two-seam fastball he used to strike out Jake Marisnick:

Look at those two pitches, and it starts to make a little more sense that Woodruff is switching away from four-seam fastballs. His two-seam complements his slider extremely well, and the four-seamer wasn’t lights-out anyway. Why not tailor your fastballs to flatter your breaking balls?

Even though Woodruff has changed his fastball mix significantly, he still throws his four-seamer a lot. Some offseason work has changed how that pitch looks, however. First, as I mentioned, he’s throwing it marginally harder. As you might expect, that’s generally a good thing for run prevention. Second, he’s spinning it more — his spin rate has increased from the 17th percentile to 37th among four-seam fastballs. This gives him more to work with, and he’s harnessed the added spin well: his four-seam now rises more relative to gravity than it ever has, despite being in the air for less time due to the higher velocity. Put it together, and the pitch has simply gotten better — it’s generating swinging strikes 14.5% of the time, up from 8.8% last year.

There’s an additional benefit to adding new pitches, one that goes beyond efficient pairing with an offspeed pitch or optimizing spin. This might seem obvious, but now that Woodruff has more pitches, he simply has more looks to give hitters. Major league hitters are tremendously good at their jobs. Throw them the same pitch a few times, and it almost doesn’t matter how good the raw stuff is — they’ll find a way to track it. People hit home runs off of Jordan Hicks, after all, and he throws 102 with sink when healthy. Without that level of electric stuff, Woodruff is highly incentivized to keep hitters off balance, and the new fastball helps out tremendously in that regard.

In 2018, Woodruff threw 574 pitches that weren’t the first pitch of an at-bat. These 574 pitches are all chances to double up by throwing the same pitch the batter has just seen — a four-seam following a four-seam, or a slider after a slider. 2018 Woodruff threw so many four-seam fastballs that he doubled up frequently — 47% of those 574 pitches he threw were the same pitch as the last one he’d thrown. In other words, hitters were getting a second chance to react to a pitch they’d just seen almost half of the time. It stands to reason that they would do a better job with that pitch, having just seen it.

This year, Woodruff has already thrown many more innings than last year, and many more pitches — 1143 pitches that weren’t the first pitch of an at-bat so far. The addition of an extra fastball, though, has made him far less repetitive — only 33% of his pitches double up with the previous pitch. This decreasing predictability is driven exclusively by his new sinker — he’s already thrown 177 pairs of two-seam back-to-back with four-seam, pairs that would have been repeated four-seam fastballs last year.

The difference between the two fastballs can seem small, but think of it this way: if Woodruff were to release his average two-seam fastball and average-four seam fastball from the exact same release point on the exact same trajectory, they’d cross home plate at almost the exact same instant, only five inches apart. Five inches might not sound like much, but when you’re working with margins as small as trying to hit a baseball with a bat, it matters tremendously. Want a good reason why Woodruff’s four-seam fastball went from the 45th-percentile to the 85th-percentile swinging strike rate with only a marginal increase in velocity, movement, and spin? Look no further than his ability to pair it with a two-seamer to stay one step ahead of batters.

A new two-seam and retooled four-seam aren’t the only reasons Woodruff has excelled in 2019. His slider has gained consistency — he tinkered around with its tilt and velocity in 2018, whereas this year’s pitch has been stable around 88 mph with consistent break. That consistency has also unleashed his changeup, which is a perfect complement to the slider. Despite extremely similar velocity and vertical movement, the pitches end up 11 inches apart horizontally when they cross the plate. Every pitch Woodruff throws works together this year in a way they simply didn’t in 2018.

If you’re looking for evidence that players can improve themselves, read The MVP Machine. If you’re looking for that evidence on the 2019 Brewers roster, though, or just want to read it on FanGraphs, look no further than Brandon Woodruff. In a single offseason, he tinkered with his pitch selection and mechanics and completely changed his outlook. A mid-level, replaceable bullpen piece last year, he’s one of the 20 best pitchers in baseball by fWAR so far this year. He’s a modern-day success story, proof that ingenuity and design can still get you ahead in a world of freakish athletes and year-round training.

Brandon Woodruff didn’t reach a new level physically. He didn’t wake up and add three miles per hour to his fastball, or develop a world-destroying breaking ball out of nowhere. He made incremental improvements to all of his pitches, but he also worked out a way to combine what he already had into a more effective whole. Woodruff’s star turn is my favorite archetype of baseball story, and one of the reasons I love the game so much: in a sport governed by fast-twitch muscles and split-second reactions, there’s still room to get ahead by careful consideration, by coming up with a plan to wring every last drop out of your own natural talents and executing that plan.