The Cubs’ Tyler Chatwood signing, by the numbers

The Cubs decided to turn up the heat on the hot stove today by signing free agent righthander Tyler Chatwood, so it seemed worth taking a look at the numbers that may have inspired them to offer the almost 28-year-old a three-year $38 million contract.

Before we dive into a look at some stats and numbers, I want to be really clear about something: Chatwood looks like a high upside guy, but there is a very real chance this doesn’t work out well. While I could probably say that about any pitcher, it feels particularly true here. Chatwood has had Tommy John surgery twice and has never pitched over 160 innings in a season. Additionally, anyone who took a brief look at Fangraphs when this news broke will be forgiven for looking at his 2017 ERA of 4.69 and 2017 FIP of 4.94, scratching their head a bit at this signing, sighing, and returning to their day. Luckily for Cubs’ fans, these are the Theo-Jed Cubs and if you look beyond the basic numbers there are a few intriguing things going on with Tyler Chatwood.

Pitch Type

Chatwood changed his pitch repertoire pretty significantly in 2016 after coming back from Tommy John surgery, and tweaked it again in 2017. You can see it pretty clearly in these charts from Brooks Baseball:

Brooks Baseball

Brooks Baseball

Brooks Baseball

The most obvious differences are that he’s throwing his Sinker less and he’s relying on his Slider and Curveball more. In a conversation with Fangraphs last year he was explicit that he changed his grip and how he throws a few of those pitches, the hidden gem in this interview is that changing the way he approached those pitches resulted in more movement, and more swinging strikes:

The pitcher did adjust how he throws the change. It’s the same grip, but thrown differently. “Just switched the way I throw it in my hand,” Chatwood said. “Grip it like my sinker and throw it off the fingers.” He switched the seams slightly, from a four-seam-type changeup grip to a two-seam one, and that may be why it’s getting more sink right now. Relative to his four-seam fastball, it’s dropping five inches now, and it used to drop an inch and a half.

It does look like all of Chatwood’s pitches have more “ride,” so some of this could be due to calibration issues in the pitch-tracking data, so it’s good to know that some of the added confidence in the changeup has come from a mental change as well. “I always used to try to make it move rather than just throw it,” he admitted. “Mine’s hard right now, but I’m getting swings and misses, because the arm speed is a big deal.” Relevant: the swing rate on the change is up to 60% from 40% last year.

Reinventing those pitches may explain Chatwood’s swinging strike rate from 2013 to 2017, which improved from 6.9% to 9.9%, as you can see in the last column below:

Fangraphs

Ground Ball Percentage

Chatwood is an extreme ground ball pitcher. In fact, if he’d have had enough innings to qualify last year, he would have ranked fifth behind Dallas Keuchel, Marcus Stroman, Luis Perdomo and our old pal the Clayton Richard Experience. His 58.1 percent ground ball rate should lead to a lot of outs with the Cubs’ top-tier infield defense of Anthony Rizzo, Javier Baez, Addison Russell and Kris Bryant.

A note of caution here: While the ground ball rate looks awesome, the HR/FB rate looks terrible. In fact, of that same arbitrary group of pitchers who threw at least 140 innings, his 22 percent HR/FB rate is the worst in baseball. There is reason to believe that that may be an effect of Coors Field (Home HR/FB: 28.6 percent, Away HR/FB: 17.9 percent.) However, Wrigley Field isn’t exactly known as a pitcher’s paradise, and we could be in for some adventurous outings if Chatwood is pitching on a day where the wind is howling out towards Lake Michigan.

Spin Rate

Eno Sarris had a great piece Thursday that looked at Chatwood’s spin rate on his breaking pitches relative to other pitchers, and it turns out those numbers are not just good, they are excellent. Without getting too far in the weeds on spin rate, this is important because spin rate tells us a lot about pitch movement, and that can be indicative of the effectiveness of a pitch.

Sarris hypothesizes that with some arm slot experimentation and a move away from Coors Field, Chatwood has the potential to really improve his pitches going forward if he can effectively use that improved spin rate.

A tougher fix may be for him to raise his arm slot, thus converting more of that spin into movement on the fastball and curve, a little like what Rich Hill did. Is it simple? Depends on the pitcher and his willingness to experiment. When I last spoke with Chatwood, he was willing to talk spin and was using his four-seam more to “mirror” his curveball spin. That sounds a lot like what Hill said after he broke out. In fact, I’ve included only his second-half percentiles above because he altered his pitching mix after our conversation and improved his changeup.

There’s a real potential for Chatwood to be more of an over-the-top, four-seamer/curveball/slider guy going forward. You see it in his strengths — velocity and spin — and also in his home/away splits. No, not the results-based ones. Coors affects movement, too. Consider how much better Chatwood’s pitches look when you use his second-half away movement and avoid that Coors effect.

I really encourage you to read the whole piece, and take a look at the charts within it. It does seem like there are some compelling numbers that indicate Chatwood may be very close to a large breakthrough. If that’s true, the Cubs have certainly made a wise investment

Not a late-inning guy

For the foreseeable future Chatwood appears to be a back of the rotation guy. This is likely fine since the Cubs already have Jon Lester, Jose Quintana and Kyle Hendricks on their roster. As you’ll see below, when Chatwood faces a hitter for the third time in a game, his numbers are pretty scary, and that leads me to believe that Chatwood will be capped at twice through the batting order. His ERA jumps from 2.35 first time through the order to 7.44 third time through the order. While a lot of pitchers show similar declines in later innings, I think, at least initially, Chatwood days are days where Joe Maddon is going to need to go to the pen around the fifth inning.

Fangraphs

Overall

In reading a few different pieces and stats about Chatwood, I’ve managed to convince myself that this is a really savvy signing by the Cubs’ front office. I’m not certain it will work out, but nothing is certain in baseball. I am seriously impressed with the potential upside, here.

I might be even more impressed with Chatwood’s willingness to experiment with new pitches, grips and arm slots. His pitch selection alone over his last three full seasons shows a lot of adaptability. This seems important for a pitcher who was compared to Rich Hill in the above Fangraphs article. I’m not predicting that Chatwood is going to have the renaissance that Hill has over the last two years, but the Cubs don’t need a top of the rotation guy, they need a fourth starter, and it looks like Tyler Chatwood has to potential to be that and maybe a little more.