Strikeouts have always been important in fantasy baseball, but with starting pitchers logging fewer and fewer innings these days, finding guys with high strikeout rates to maximize every inning is more essential than ever. Only 13 pitchers logged 200 innings last year and just 32 reached 180. As recently as 2015, those numbers were up at 28 and 56. The workhorse pitcher has become a rare breed, indeed.
Of course, just looking at last year’s strikeout rates won’t always tell us the whole story, so a simple way we can help identify which hurlers could improve or decline in punchouts is using swinging-strike rate (or whiff rate), a popular metric that tells us how often a player’s arsenal will induce swings and misses.
As FanGraph’s Alex Chamberlain has astutely pointed out, strikeout rates are generally around double that of swinging-strike rates. In the case of starting pitchers in 2018, they averaged a 21.6% strikeout rate and a 10.2% swinging-strike rate.
There will always be exceptions to this general rule (Aaron Nola), but this at least gives us a starting point when trying to unearth this year’s risers and fallers in strikeouts. Let’s take a look at some of 2018’s biggest discrepancies between strikeout rates and whiff rates and what they mean for this year.
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2018 Strikeout Rate: 25.0%
2018 Whiff Rate: 14.1%
For the second season in a row, Masahiro Tanaka put up an elite swinging-strike rate, boasting a 15.1% mark in 2017, followed by 14.1% last year. Among pitchers with at least 150 innings in 2018, he ranked ninth in the metric just behind Justin Verlander and James Paxton and tied Gerrit Cole — all guys who posted strikeout rates above 30%.
So, while Tanaka produced a strikeout rate right around 25% in both seasons (25.8% in 2017), which is plenty good already, is there a chance there’s room for more growth? His rise in both strikeout rate and whiff rate is directly connected to throwing his slider and splitter more often, easily his two best pitches. In 2018, Tanaka’s slider registered a 27.4% strikeout rate, 15.6% whiff rate, and only allowed a .238 wOBA, while the splitter tallied a 32.1% strikeout rate, 23.0% whiff rate, and .271 wOBA. It’s no wonder he threw those pitches roughly a combined 65% of the time.
Assuming Tanaka keeps that usage up, it sure looks like the skills are there to keep upping that strikeout rate. Another positive sign is he’s continued to show great control even with the rise in punchouts, including a career-high 68.2% first-strike rate that ranked sixth-best last year to go with his usual low walk rate (5.5%). He also maintained a solid 3.50 SIERA, supporting last year’s sub-4.00 ERA.
Of course, the knock on Tanaka has always been the long ball, as he allowed 1.44 home runs per nine innings last season and owns a miserable career 16.4% HR/FB rate. Maybe there’s still some bad luck in there, but particularly at hitter-friendly Yankee Stadium, it’s a blemish that could be tough to rectify. Health also remains an issue given that Tanaka has thrown fewer than 160 innings in three of his five MLB seasons.
But as a guy going around pick 130 in early drafts, we have to like the value and upside we’re getting here. Tanaka has routinely put up good numbers, and with added health and a dip in those home runs — plus that strikeout potential — there could still be another level to his game.
2018 Strikeout Rate: 23.3%
2018 Whiff Rate: 13.5%
A popular breakout candidate in 2018, Luis Castillo disappointed fantasy owners with an absolutely brutal first half (5.49 ERA), but a strong rebound in the second half (2.44) reminded everyone what the hype was all about.
Looking at just those second half marks, Castillo posted a 3.30 SIERA and 26.3% strikeout rate, a far better reflection of his high whiff rate and much more like the 2017 version of Castillo that got everyone excited in the first place. Additionally, he put up a stellar 5.3% walk rate, backed by an improved 63.4% first-strike rate, and also saw his ground-ball rate go up (48.0%).
That post-All-Star break surge was supported by an uptick in velocity and coincided with a rise in the usage of his change-up. In 2018, that change-up generated a whopping 43.4% strikeout rate, 26.8% whiff rate, and .239 wOBA allowed.
So, despite an overall underwhelming sophomore campaign, we’re basically right back where we started with Castillo as a potential high-upside pick. It remains to be seen if he can put it all together across 30 starts, but with an ADP outside the top-100, it might be hard to resist finding out.
2018 Strikeout Rate: 25.4%
2018 Whiff Rate: 13.1%
We keep hoping for the 2015 Chris Archer to come back, but he just keeps letting us down. However, 2018 was especially disheartening, with Archer posting just a 4.31 ERA and 1.38, easily his poorest marks across the past six seasons. Worst of all, after posting 200-plus innings and 230-plus strikeouts in each of the prior three years, injuries held him to just 148 1/3 innings and his strikeout rate drop from 29.2% to 25.4%, leading to just 162 punchouts.
And yet, his 13.1% swinging-strike rate remained excellent, pretty much exactly in line with the previous season (13.4%), and his walk rate (7.7%), first-strike rate (62.1%), and velocity were all within his career norms as well. Really, this seems like the same guy who racked up all those strikeouts from 2015-2017.
Everything points to Archer being a strong candidate to bounce back in 2019 and at an ADP barely inside the top 130, we’re no longer paying for that elusive 2015 repeat. A recent trend of giving up long balls and hard contact isn’t ideal, but last year’s 3.73 SIERA and .338 BABIP suggest we should give him a pass on the ERA, and a sub-4.00 mark is still a distinct possibility. With a clean bill of health, it isn’t unreasonable to expect Archer to get back in the neighborhood of 200 innings and 200 strikeouts — something we don’t see very much of anymore.
2018 Strikeout Rate: 27.2%
2018 Whiff Rate: 10.3%
On the other side of the coin, Mike Foltynewicz enjoyed a breakout 2018 campaign, producing career-bests in four standard roto categories with a 2.85 ERA, 1.08 WHIP, 202 strikeouts, and 13 wins. The punchouts were the byproduct of two other personal bests — 183 innings and a rise in his strikeout rate from 20.7% to 27.2%.
It was the sort of brilliant campaign folks have been hoping to get out of Foltynewicz for a while now, but he figures to come back down to earth. Despite that massive leap in strikeout rate, his swinging-strike rate was a hair below the league average (10.3%) and barely above his career rate (9.7%), making it difficult to trust that his gains will stick. Furthermore, for a guy with a career 4.22 ERA, it probably isn’t surprising his 3.77 SIERA sat well above last year’s ERA, which benefited from a fortuitous .251 BABIP.
That isn’t to say that Foltynewicz doesn’t have the goods for another strong campaign. The breakout wasn’t a total fluke, as he has big-time velocity (over 96 mph) and upped his slider usage — a pitch that produced a 41.8% strikeout rate, 18.7% whiff rate, and allowed a .177 wOBA in 2018. There’s still plenty to like here, but with an ADP often going around pick 80, you’re paying a premium price now and regression looks inevitable.
2018 Strikeout Rate: 26.3%
2018 Whiff Rate: 10.4%
When a 35-year-old posts a career-high in strikeout rate that’s typically a red flag, although in the case of J.A. Happ, we can point to an increase in fastball usage and drop in sinkers — generally a less effective pitch — as an explanation for the improvement. Still, with a career 20.9% strikeout rate and only a one percentage point gain in whiff rate from 2017, it’s difficult to imagine him enjoying the same strikeout success in 2019.
Happ has posted a sub-4.00 ERA over the past four seasons and has a strong chance for wins on the Yankees, so even with a dip in strikeouts, he could put together another solid campaign. It’s just that now he’s going about 100 picks earlier than last year, and guys like Tanaka, Archer, Carlos Martinez, or Yu Darvish arguably all offer more upside around the same price range.
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Kenyatta Storin is a featured writer with FantasyPros. For more from Kenyatta, check out his archive and follow him @kenyattastorin.
