Maybe It Is a Bad Idea to Pitch in the WBC

The Seattle Mariners went into the offseason with a solid lineup and a questionable at best starting rotation, which was made even more so with the trade of Taijuan Walker for Jean Segura and Mitch Haniger on November 23rd, 2016. On January 11th, 2017 GM Jerry Dipoto made his eleventh trade of the offseason when he shipped off the recently-acquired Mallex Smith along with minor leaguers Carlos Vargas and Ryan Yarbrough to the Rays for lefty Drew Smyly.

In 2016, Smyly put up a rather uninspiring 4.49 FIP, but he did take the mound 30 times and throw a career-high 175.1 innings. He wasn’t supposed to be anything special for the M’s; he was just supposed to slot into the middle of their rotation behind James Paxton and Felix Hernandez.

That is, until March 15th, when he started for the US in their World Baseball Classic game against Venezuela and Seattle teammate Felix Hernandez. If you don’t remember what happened that night, go read this article by Jeff Sullivan. Smyly was brilliant, allowing 0 earned runs on only 3 hits. He did not issue a walk, and had 8 strikeouts in 4.2 innings. Felix was just as good that night, going 5 shutout innings with no walks and only 3 hits allowed. But what caught everyone’s eye was the uptick in Smyly’s fastball velocity. As Jeff detailed, his fastball was more than two ticks above his career average, and this was coming in a mid-March start. Mariners fans had to be thrilled after watching that game. Was the King back? Had Dipoto traded for another power lefty starter to pair with Paxton? Smyly was also elated, saying a couple days after that start, “hopefully, I can carry that with me for the rest of the season, but it’s a long season. … It’s hard to maintain that for 30 starts, but if I can, that’ll be great.”

Well, in late March, the Mariners put Smyly on the DL with elbow discomfort, and then on Wednesday, Ryan Divish of the Seattle Times broke this news:

As an M’s fan, it was a big blow to go from hoping for 30 starts of this new harder-throwing Smyly to knowing that he won’t even throw a pitch for the M’s this year (if ever). Smyly wasn’t the only Mariners pitcher to participate in the WBC and then have issues this season. I already mentioned that Felix started that same WBC game for Venezuela, and he spent two months on the DL with shoulder bursitis before returning on June 18th. Yovanni Gallardo threw 4 innings for Mexico, and he was terrible this year before recently being replaced in the rotation. Also, last year’s rookie closer phenom Edwin Diaz has very ineffective this year after being almost unhittable as a rookie in 2016.

This had me thinking, it couldn’t just be bad Mariners luck, could it? Have the other pitchers that participated in the World Baseball Classic gotten hurt and/or been less effective this season? Could all those complaints and worries about the WBC messing with throwing schedules and programs be justified?

So, I gathered the data to look at how MLB pitchers who participated in the WBC have performed this year. I am comparing their 2017 season results to how they performed from 2014 – 2016. This is a very simple comparison, and there some caveats that you should know about the data I am using: I am only including pitchers who threw at least 3 innings in the WBC, I removed 4 pitchers who made their debut in 2017, and I also removed Drew Smyly since he hasn’t pitched in 2017. I do, however, leave in everyone who made their debut prior to 2017. For example, Jose Berrios is included in the sample although only he only had 58.1 career innings before 2017, all of which came in 2016. This leaves me with a sample of 36 pitchers who have pitched before and after participating in the year’s WBC. Now let’s get to the results!

First, here is the comparison of 2017 vs 2014 – 2016 for the sample as a whole using a weighted-average approach:

2014 – 2016 3.49 3.73 3.84 88 93 96
2017 4.30 4.30 4.43 99 99 102

As you can see, quite a decrease in performance by our group in 2017. In fact, the sample group has been almost exactly league average in 2017. While the WBC rosters are not entirely comprised of All-Stars, I think we would assume that the players competing for their countries in the biggest international baseball tournament are better than league average, and the data from 2014 – 2016 suggests that they were.

Now, to look at this individually, here is a scatter plot comparing the FIP- from 2017 vs 2014 – 2016 for the 36 individual pitchers:

Clearly, we can see that there are some outliers that have performed much worse in 2017 than they did in the previous years. On the very right we have Sam Dyson (2017: 156, 2014 – 2016: 82), who was designated for assignment by Texas after his historically bad start to the season as their closer, and moving down from him to the left is Edwin Diaz (126, 48). But these outliers are made up for by Jose Berrios, who we see at the very top has been significantly better this year than in his first taste of the show last year (77, 145). So, we cannot attribute this decrease in performance to the outliers, but rather by the group performing worse, which we can see by how close most of the group is to the trendline, in addition to the Average point being located to the left of the trendline.

Here are also the biggest increases and decreases in 2017 performance compared to 2014 – 2016:


2017 FIP- 2014 – 2016 FIP- Change

Jose Berrios

77 145


Pat Neshek

47 82


Fernando Rodney

76 98


Danny Duffy 82 100


Chris Archer

68 85


Carlos Martinez

76 86





2017 FIP-


2014 – 2016 FIP-



Edwin Diaz

126 48


Sam Dyson

156 82


Seung Hwan Oh

105 52


Hansel Robles 143 92


Warwick Saupold

101 54


Julio Teheran 137 102


Felix Hernandez 120 88


The point of this article is not to say definitively that the World Baseball Classic has caused this group of pitchers to suffer a decrease in performance and/or injuries. I realize that this decrease in performance could be completely random, and we only have a half season of data after the 2017 WBC, but I do think it is interesting that the group has performed worse in 2017 than they did in the previous years. There has been lots of discussions about when the best time to hold this tournament would be, or if it is even worth having at all. Maybe it is a bad idea to have this tournament before the season starts when the arms aren’t fully stretched out. Maybe teams won’t allow their top pitchers to participate in future tournaments. Or, maybe it is just a bad idea to pitch in the WBC.

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Marty McFly
Marty McFly

I’ve always wondered if this was why big name pitchers sit it out sometimes.

It would be interesting to see the numbers for pitching across the league from ’14-16 compared to ’17 as a baseline. Also, do the same study looking back at the previous 3 yr performance comparatively to pitchers who were in the WBC other years vs. the rest of the league, as well.

You may be on to something, but as you say it’s hard to tell if it’s just noise or an actual pattern. Nice insight, though.


Stroman and Berrios are pitching well after hurling in the WBC so it is not all doom and gloom . . .


Or maybe #theballsarejuiced


Have it after the season perhaps


There is some selection bias here, since the reason players get invited to the WBA is the fact that they have had unusually good seasons leading up to it.

I think the real test would be to see if they are truly under-performing their projections, on average.