Pittsburgh Pirates: What to Expect From Trevor Williams in 2020

Pittsburgh Pirates starting pitcher Trevor Williams followed up an impressive breakout season with a poor 2019. So what should you expect from him next season?

There is no way to sugarcoat it, Trevor Williams had a disappointing 2019 season for the Pittsburgh Pirates. Hopes and expectations were high for the right-handed starter after a good 2018 campaign.

In 2018, Williams pitched 170 innings to the tune of a 3.11 ERA, 3.86 FIP, and 1.18 WHIP. Last season for Williams, those numbers rose to both an ERA and FIP above 5 (5.38 and 5.12), while also seeing his WHIP take a sharp spike up to 1.41.

So what went wrong in 2019 that Williams can improve upon? If he can improve upon those factors, what should you expect Williams to contribute to the Pittsburgh Pirates whenever the next season starts?

First, we should look at the ERA estimators. Sometimes those can paint the picture of what happened from year to year. In 2018, Williams still carried sub-par overall estimator numbers. Those include a 4.54 xFIP, 4.68 SIERA and 4.28 DRA. Those indicate that his ERA of 3.11 in 2018 was a bit flukey.

In 2019, long time Pittsburgh Pirates nemesis Adam Wainwright had very similar numbers to Williams in 2018 and he had an ERA of 4.19, over a run higher than Williams. But his ERA estimators took a jump from 2018 to 2019. His xFIP was 5.25 while carrying a 5.08 SIERA and 5.74 DRA. When all of your stats, your ERA estimators, your ERA and your FIP all are within a run of each other, it means you pitched to your expected results, and Trevor’s expected results just weren’t very good. Another major sign of regression for Williams between 2018 and 2019 was his batting average on balls in play. After posting a .291 BAbip in 2017, that fell 30 points down to .261 in 2018. In 2019, it rose back to over .300 to .303. Part of that rise is likely due to the rise in exit velocity as it rose to 87.5 MPH after sitting in the mid-to-low 85s in seasons prior.

So what exactly happened between 2018 and 2019? Well it wasn’t a drop in strikeouts, or increase in walks. In 2018 his walk rate was 7.8% while his strikeout rate was 18%. The following season, those numbers were still solid with a 6.9% walk rate and 17.8% strikeout rate. But what really bit him was the home run and his batted ball results.

Last season, Williams surrendered 27 home runs. That’s a dozen more than he had allowed in 2018, but he faced 65 fewer batters in 2019. Now this is not a big shocker. Home runs were up across the board. The average home run rate the previous season was 1.4 per 9. In 2018, the home run rate was 1.2. He also saw his hard hit rate go from 29% in 2018 to 33% in 2019.

I think one of the main contributing factors to the struggles Willliams encountered on the mound in 2019 was who he was pitching to. 32.3% of all of his innings were pitched  when Elias Diaz was behind the plate. Diaz had an awful season defensively with -21 DRS, -1 stolen base runs above average, and, the most important stat I want to focus on, -14.4 framing runs saved.

That was the lowest mark in the MLB in 2019. Williams’ results were awful when Diaz was behind the plate, surrendering 16 home runs, an opponent OPS of 1.081, and a 8.87 ERA with a 7.12 FIP. When either Francisco Cervelli or JAcob Stallings were behind the plate, both of who are considered above average framers, that ERA dropped to 3.67, and his FIP fell all the way to 2.81. If Williams pitches to a guy like Stallings, who had +14 DRS, caught 36% of all runners trying to steal on him, and 8.7 framing runs, this should help his performance.

Another possible contributing factor of Williams’ struggles could be his pitch usage. Williams has four pitches at his disposal. These four pitchers are a fastball, sinker, change up, and slider. His fastball usage stayed pretty much the same between his breakout 2018 to his 2019 season, but his other pitches saw massive changes in usage.

In 2018, Williams’ sinker was his second most used pitch at 18%. He held opponents to a wOBA of just .301 with it. In 2019, he only threw the pitch 15% of the time, and became his second least used pitch. His change-up also saw a slight decrease in usage going from 15.3% to 12.1%, making it his least used pitch in 2019. But it’s his slider that saw the biggest change in how often it was used. After throwing it 15.1% of the time in 2018, that rose to 20.1% in 2019. Now yes, it was his most effective pitch in 2018 (28.3% whiff rate, 16.7% put away rate), and in 2019 (31.3% whiff, 23.6% put away), but the large jump in usage combined with a decrease in effectiveness (.272 opponent wOBA to .348 opponent wOBA) could be an indicator that he wasn’t comfortable with using the pitch so often. Hopefully, the new coaching staff can either help Williams get comfortable with a new repertoire, or help him go back to what was effective in 2018.

Whenever the 2020 season starts, Williams should bounce back from an awful 2019 season. Things like a new pitching coach for the Pittsburgh Pirates and a much better defensive catcher, better defense behind him overall as eventually elite defenders Cole Tucker and Ke’Bryan Hayes will take over full-time roles, and an unjuiced ball are all working in Williams’ favor.

Now I don’t think we’ll ever see his ERA drop to the low-3s. But that doesn’t mean he won’t be effective. His results likely point to something in between his 2017 and 2018 season. That comes out to a pitcher with a 3.56 ERA, 3.94 FIP and 1.24 WHIP who doesn’t give up many home runs (0.8 HR/9), and carries a usual strong walk rate below 8%. If anyone is interested in Williams’ projections, Baseball Reference says he would currently have a 2.25 ERA 1.13 WHP, but 4.34 FIP through 28 innings and five starts had the season started on time.