Breaking Down Trevor Williams Rookie Season

Trevor Williams entered the season as rotation depth, and ultimately ended with a job in the bullpen as the long reliever.  He ended up in a starting spot due to unfortunate circumstances, and he exceeded his overall expectations in that role.

One of the things that Neal Huntington talks about is acquiring pitching depth, and having Major League quality starting pitching depth in Indianapolis.  Pitching, an expensive cost on the open market based on recent contracts, is always an area of need and being able to acquire controllable pitchers for minimal cost is usually sound strategy.  After Marc Delpiano left the Pirates in September of 2015, Jim Benedict soon followed, though the Pirates wanted compensation, which occurred in the form of Trevor Williams for Richard Mitchell.

The addition of Williams gave the Pirates a starting pitching prospect to plug immediately into Triple A to go along with Tyler Glasnow, Steven Brault, Jameson Taillon, and Wilfredo Boscan.  This gave the Pirates four young arms who are controllable and costs are low, though they did all have no Major League experience.

This led to Williams starting 19 games, with an additional game in relief, for the Indianapolis, where he posted a 2.53 ERA in 110.1 innings.  He got called up with expanded rosters in September, and made his big league debut on September 7 against the St. Louis Cardinals, pitching three innings yielding one unearned run, though there was more to the game than just his performance.

Fast forward a few months and Trevor Williams is competing for a spot in the rotation for 2017, but he ultimately was sent to the bullpen.  Williams overall had a strong rookie season, posting a 96 ERA- and 95 FIP- in 150.1 innings, essentially being five percent better than average, a very quality mid to backend starter – though his Deserved Run Average of 3.95 and DRA- of 84.1. leading all Pirates starters, might indicate better things are on the horizon for Williams.

Trevor Williams was underperforming his FIP for most of the season, though it finally converged towards the end.  He also got better as the season continued, getting to pitch every fifth day and having a set routine over being a long reliever does help.  Below is his progressive ERA, FIP, and RA9 for his career (by clicking the Tableau you can scroll right and left to view other dates):

It follows a nice trend of getting better each time out, something that is always a good to see in a pitcher.  Before the season, ZiPS projected a 4.66 ERA and 4.61 FIP, Steamer projected a 4.54 ERA and 4.37 FIP, and PECOTA had him projected at a 4.59 ERA and 4.76 DRA.  He outperformed all three, pitching to a 4.07 ERA, 4.03 FIP, and 3.95 DRA.

Williams, who will be 2016 next season, was able to outperform projections and continue to improve each start mainly by generating soft contact.  Williams generated 463 batted balls and had an average exit velocity of 85.0 mph, ranking ninth best among pitchers with 400 batted ball events.  He limited opponents to a 29.4 percent hard hit rate (batted balls over 95+ mph), which ranked 12th among those with 400 batted balls.  Below is his hard hit percentage compared to the league:

Williams only had one month in which he was above the league average, occurring in June, which happened to the month he posted his lowest walk, which helps.  But limiting hard contact is great, getting soft contact is very important, and so is getting the ball on the ground.  Williams posted a 48.0 percent ground ball rate, where the league is at 44.2 percent.  Williams was getting soft contact on the ground, which limits the chances of hits and home runs, which Williams only allowed a home run 2.2 percent of the time compared to the 3.3 percent by the league.

His BAbip of .291 isn’t too low, league was at .297, Williams generates soft contact, and his estimated wOBA based on exit velocity and launch angle (xwOBA) was .313 and his wOBA was .312.  Williams performed about where he was expected to in terms of batted balls.  Getting soft contact is great, but missing bats is even better.  Below is his progressive strikeout, walk, and unintentional walk+hit by pitch rates:

Williams strikeout rate started to trend upward after July, though his highest strikeout in a month in 2017 occurred at just 23.7 percent (September/October), and league average for the season was 21.6 percent.  Williams walk rate also increases, but it mainly went to the rate he had before July.  His 8.1 percent walk rate on the season was right in line with the 8.5 percent the league had.  His swinging strike percentage of 8.3 percent was well below the league average of 10.5 percent.  That is an area where hopefully there can be an improvement, but perhaps the tradeoff is more hard contact and walks, and at what point is that a concern going in the opposite direction?

Next: 2017 Draft Recap: Dylan Busby

Williams generated a lot of soft contact and improved as the season went along, and his ERA merged closer to his FIP after underperforming for so long.  He was a league average starter in terms of ERA and FIP once adjusted to the park and league, though his DRA shows more promising results.  Williams will be in the rotation next year, he earned that after having a solid showing as a rookie, and he appears to be a strong back of the rotation arm moving forward.

Numbers from baseball prospectus, fangraphs, and baseball savant