Cubs: Regression monster coming for Trevor Williams, Jake Arrieta

Chicago Cubs right-hander Trevor Williams had what appeared to be another strong outing on Tuesday evening.

Williams kept the Cubs in the game early, giving up two runs in five innings of work before the bullpen imploded. It was the third straight start in which Williams went at least five innings and allowed two or fewer runs.

Chicago’s rotation is seemingly being held together by Williams and Jake Arrieta with both Kyle Hendricks and (especially) Zach Davies struggling early and Adbert Alzolay still getting a feel for things.

Cubs: Make no mistake about it, regression is coming for Williams and Arrieta

Let’s start with Williams, because there are some reasons to be encouraged. The 29-year-old has 27 strikeouts in 24 1/3 innings. He has given up just two homers after giving up an MLB-high 15 in 2020.

Williams is getting more from his swing-and-miss stuff. He ranks in the 69th percentile in whiff rate after ranking in the 31st percentile in that category in 2020, per Baseball Savant.

However, Williams is giving up oodles of hard contact. In fact, his 92.4 MPH average exit velocity is the highest of his career, as is the 49.3 percent hard-hit rate.

Tuesday night’s game was an interesting window into possible regression. The Atlanta Braves peppered Williams with eight batted balls of at least 90 MPH, the most notable being a Ronald Acuna Jr. blast that traveled a whopping 481 feet.

Now, Williams got 15 swings and misses. He managed to work around the contact. But he will likely be hard-pressed to keep doing so as the season rolls along.

What about Arrieta?

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The 2015 National League Cy Young Award winner has a 2.57 ERA and 3.44 FIP in his first five starts. He has gone at least five innings in each of his outings, tossing six innings on three separate occasions. Again, though, the standard numbers do not tell the whole story.

Right off the bat, Arrieta has not faced strong competition. He has made two starts against a Pittsburgh Pirates team ranked last in the NL in OPS and two more against another underwhelming lineup in Milwaukee, with the Brewers leading the NL (second in the majors) in strikeouts. Arrieta’s other start came against the New York Mets, a team that can’t hit the broad side of a barn right now.

Additionally, like Williams, the batted ball numbers just aren’t good. Arrieta is giving up the highest average exit velocity (90.6 MPH) and hard-hit rate (40.5 percent) of his career.

Something else to watch with the veteran right-hander: the ground ball rate. It’s at just 35.4 percent right now as compared to a 34.2 percent fly ball rate. Arrieta usually hovers closer to 50 percent in ground ball rate.

The strikeout rate is up, which is a positive, but it does not negate all the hard contact. Plus, despite the strikeouts, Arrieta doesn’t exactly miss bats. He ranks in the 24th percentile in whiff rate.

Perhaps both Williams and Arrieta can gut it out and continue to be effective for a Cubs team that desperately needs quality starts, particularly with the bullpen really starting to struggle. But it seems like just a matter of time before the regression monster rears its ugly head.