2018 in Review: Tyler Thornburg

Welcome to the Red Sox Review series. It’s a fairly standard feature in which we will review the year that was for every player who made a decently large impact on the Red Sox this year. How do we come up with that definition? Completely arbitrarily, of course! The list of players we’re using can be seen here, and if we are missing anyone please let me know in the comments. Anyway, for the players who are included we will wrap up their season in a sentence, look at the positives of their 2018, the negatives, review their One Big Question from the preseason (when applicable!) and look ahead to what’s on the table for 2019. Today, we discuss Tyler Thornburg.

The Year in a Sentence

Tyler Thornburg finally made his way to a major-league mound for the Red Sox in 2018, but he didn’t inspire much confidence that he could get back to the level he’d reached in his final season with the Brewers.

The Positives

If we’re being honest with ourselves — and we should always strive to be honest with ourselves, right? — there weren’t a whole lot of positives from Thornburg’s 2018. You probably could have guessed that from the Year in a Sentence above if you somehow didn’t know it from watching the 2018 season. Still, there were some positives, and number one was just the simple fact that he pitched at all. Now, is part of this that we have set the bar incredibly low for Thornburg? Absolutely! Still, he hadn’t pitched in a Red Sox uniform after being acquired in December of 2016 and the TOS surgery he underwent is certainly no joke. It’s a procedure that has ruined multiple careers over the years and Thornburg could have never come back. But he did! The righty pitched in 25 major-league games and tossed 24 major-league innings in 2018. It’s a step!

Photo by Ed Zurga/Getty Images

He also gave some reason for confidence very early in his comeback attempt. Thornburg did miss most of the first half, but came back right around the halfway point of the season. (The real one, not the All-Star break.) His first appearance in a Red Sox uniform came on July 6 in Kansas City. The first two outings of his comeback attempt were not great, with clear rust showing on the mound and runs being allowed in each. After that, he started to settle in and look like he was hitting a groove. It wasn’t utter dominance, to be fair, but he showed flashes. After those first two outings, he allowed just three runs (all in one outing) over his next nine appearances and 8 ¹⁄₃ innings (3.24 ERA) with over a strikeout per inning and allowing a .536 OPS. Expanding it a little further, over his next 15 outings and 14 innings he pitched to a 3.21 ERA with exactly a strikeout per inning while allowing a .639 OPS. There were signs of some trouble, most notably control, but if you squinted you could see a good major-league reliever in there.

Speaking of squinting, if you want to keep looking for positives you can go to Thornburg’s splits page on Baseball-Reference. It’s honestly not overly informative since we’re talking about splits on a 24-inning season, but it’s something. Specifically, Thornburg was much better at Fenway than on the road. When he was pitching in front of the hometown fans, the righty pitched to a 2.45 ERA while allowing a .725 OPS compared to a 10.61 ERA and a 1.119 OPS on the road.

The Negatives

While there were the aforementioned flashes for Thornburg in 2018, and the simple fact that he pitched at all was a step in the right direction, on the whole his season was largely negative. Despited some hope that when he came back from the disabled list he’d eventually work his way back into being one of the top relievers on the roster, in reality he didn’t even pitch well enough to make the playoff roster. Again, we’re only talking about 24 innings, but the numbers were bad. Over the course of his season, Thornburg pitched to an ugly 5.63 ERA with a 6.07 FIP and a 5.01 DRA. His strikeouts were down not only compared to his breakout 2016 with the Brewers but also his previous stints as a starter. His control had always been an issue, but he was even worse in 2018 with his second highest walk rate of his career. Plus, on top of all that, he was getting crushed.

It was that last part that was the biggest issue for Thornburg this year. Well, that is if you had to pick one, because the combination of everything was the real issue. Still, the righty just could not limit hard contact against major-league hitters. Although he’s always been a flyball pitcher, he’d had some scattered success at keeping the ball in the yard previously in his career despite pitching in a hitter’s park like Milwaukee (fourth-highest home run factor in the baseball, per Fangraphs). This past year, though, he did no such thing. Thornburg allowed a whopping six home runs in 24 innings, or more than two per nine innings. Home runs are up around the league of course, but not to that extent. According to Fangraphs, he actually gave up hard hits at a lower rate than he did in his breakout 2016, but hitters were able to turn around on his pitches at a much higher rate. We’ll get to the reasoning behind that in a second, but it led to some big home runs.

There are a lot of other factors we could talk about here, but maybe the most disappointing factor for Thornburg was his platoon splits. Now, to be clear, the righty was bad against both righties and lefites in 2018. Righties posted a .972 OPS and lefties posted an .800 OPS. At first glance, that OPS allowed to lefties isn’t too bad considering Thornburg is a righty. However, his ability to hinder opposite-handed hitters was one of his big selling points when he was acquired. Between Thornburg and Joe Kelly, the Red Sox wouldn’t need any left-handed relievers because they had two good righties who could shut down lefties. In 2016, for example, Thornburg held lefties to an incredible .413 OPS. To be fair, the .387 batting average on balls in play he allowed to lefties played a role here and there is some luck involved, but the Red Sox simply need to see better production against lefties for Thornburg to be the best version of himself.

The Big Question

Can Tyler Thornburg keep his stuff after undergoing TOS surgery?

This was a massive question for Thornburg coming into the year, because after he struck out over 12 batters per nine innings in 2016 the Red Sox were looking for similar dominance in his comeback. Of course, the TOS surgery can have drastic effects on pitchers and that showed with the righty this past year. As I mentioned above, his strikeout rate fell considerably, all the way down to just below eight per nine innings. The difference in his stuff was noticeable, too. His fastball velocity dropped a little more than 2 mph compared to 2016, per Brooks Baseball, which helps explain hitters being able to pull a lot of pitches off him. The effectiveness of the pitch waned tremendously as well, getting whiffs on just 5.4 percent of time he threw the pitch in 2018 compared to an 11.8 percent whiff rate in 2016. The good news is that his curveball whiff rate actually rose a bit, but he needs to be able to work off his fastball to have success.

The Year Ahead

The Red Sox opted to tender Thornburg a contract in arbitration to bring back the righty for another chance in 2019, and it could be his last chance in the majors. He’s entering his age-30 season, and he’ll likely be fighting for a spot in the bullpen in spring training. Given Boston’s tendency to heavily favor hoarding depth to start the year and that Thornburg can’t be sent to Pawtucket, he’ll have the inside track towards an Opening Day roster spot. Personally, after seeing what he did in 2018 and knowing the history of the TOS surgery, I’m not overly confident. The potential is there and we saw some flashes last summer, but if I was a betting man I’d bet on Thornburg not being in a Red Sox uniform by the end of the 2019 season.