This is the companion piece to the Hitter deep dive last week. Now that we have accumulated over a month of data, we can examine to see which starting pitchers have seen the most substantive changes (in both directions) in their pitching effectiveness, both in defense-independent results (e.g. K%, BB%) and with the underlying peripherals (Z-Con%, O-Sw%, and SwStrk%).

To identify buy-low pitchers, who we call Hot Rods, and sell high (Lemons), we looked at 2019 data for the following characteristics:

• K%
• BB%
• SIERA (Defense-independent pitching metric, on the same scale as ERA using K%, BB%, GB%)
• SwStrk% (percentage of pitches swung at and missed)
• O-Sw% (% of pitches outside of the strike zone swung at by batters)
• Z-con% (% of pitches inside the strike zone swung at where contact was made [lower is better])
• vFA (velocity of the fastball, per pitchfx)

The difference in these categories from their 2018 season was identified (note that pitchers who did not pitch in 2018, such as Chris Paddack, were not considered in this list). The starting pitchers (minimum 20 IP thrown thus far) who showed the biggest relative improvements in these characteristics are:

Enjoy the list and please click on the baseball card to visit our partner amazon.com to explore additional information on each player.

Hot Rods

Caleb Smith, Miami Marlins

*The difference is considered “positive” when it is “better” in 2019 than in 2018. A higher K% and SwStrk% rate is better; a lower BB% and Z-Con% rate is better. Therefore a K rate of 10% in 2019 (compared to 15% in 2018) will be considered a ‘difference’ of -5%. Conversely, a BB rate of 10% in 2019 (compared to 15% in 2018) will be considered a ‘difference’ of +5%. Also, the ‘difference’ is just an absolute difference in the percentages.

Friend of the podcast Tony Cincotta’s sleeper pick of 2019 has come out like gangbusters thus far in 2019 dispelling any concerns anyone might have had with his creaky shoulder. Although his fastball velocity is slightly down so far in 2019, everything else has improved substantially – both under the hood and in the results themselves. The only cold water that can be splashed on his campaign’s prospects for the rest of the season is that his left-on-base percentage (LOB%) is 90.2% suggesting that he might be getting lucky (as most pitchers can’t control this and LOB% typically regresses to the league average of around 75%). His SIERA is 3.06 though (compared to his ERA of 2.00) so even if his ERA regresses to match his SIERA, he should easily finish a top 30 starting pitcher…provided his arm holds up.

Matthew Boyd, Detroit Tigers

Another 2019 surprise this year has been Detroit Tiger starter Matt Boyd who has spun a WHIP of 0.99 and an ERA of 3.05. Everything supports those marks too, as he has vastly improved in all of these facets.

Just for fun, here are pitchers from 2018 who finished the year with numbers closest to what Boyd has put up thus far in 2019…and they all happen to be southpaws.

Pitchers A, B, and C happen to be 2018 James Paxton, 2018 Blake Snell (who happened to win a Cy Young) and 2018 Patrick Corbin. Fine company to keep if I do say so myself

Lucas Giolito, Chicago White Sox

The former top pitching prospect still has to manage his walk rate a little better (currently a lofty 11.5%) but there are a lot of reasons for optimism for the former Washington National. Despite the gaudy 5.32 ERA and 1.44 WHIP, the 6’6” right-hander actually has put up 0.4 WAR already this year and has posted above league average values for SwStrk%, Z-con%, SIERA, and K-BB%. One major change that Giolito has shown is raising the spin rate on his four-seam fastball up to 2200 RPM (from 2100 last year). You might be able to find an owner who has suffered enough frustration with Giolito that he is willing to part ways at this point. The data here suggest that that owner may be premature – especially in dynasty leagues – as Giolito has shown tremendous improvements across the board. As we know, prospect development is not linear.

Lemons

The pitchers showing the biggest negative rate changes thus far in 2019 are Shelby Miller, Brad Peacock, Nathan Eovaldi, and Chris Sale. However, I won’t talk about them for a variety of reasons: Miller hardly pitched last year (distorting his ‘2018’ numbers), Peacock was mostly a reliever in 2018 (also distorting his previous season numbers), Nathan Eovaldi has arm problems (so we already know that something’s off), and Sale’s woes have filled reams of pages in 2019 already. The next starting pitchers though, who have shown dramatic degradation in their FIP components (K% and BB%) and underlying “stuff” peripherals have some serious name power themselves. If you own them, consider yourself warned:

Masahiro Tanaka, New York Yankees

Ever since he was diagnosed with a partial tear of his UCL, Tanaka owners have held their breath waiting for the inevitable cliff-diving season…and it never came. Maybe it’s the elbow or maybe it’s just more of the same misfortune that has befallen most of the Yankees this 2019 season, but so far this year severe warning signs are flashing at Tanaka. A 1.31 WHIP and 3.92 ERA doesn’t seem terrible but, unfortunately, that’s the good news. He’s not getting anyone to chase outside the zone – long his hallmark – and he’s not getting anyone to whiff either. He’s lost some velocity, and he’s walking more batters. Since he arrived in MLB in 2014, his split-finger has always put up a positive pitch value but so far in 2019, it has a wRC+ against of 191. In other words, batters are essentially 2018 Mike Trout against the split-finger. I don’t know if he will figure it out – he is a crafty veteran so if anyone can, it’s him – but for now, we may be witnessing the decline of one of Japan’s greatest pitching exports.

Aaron Nola, Philadephia Phillies

Aaron Nola’s poor performance in 2019 has been puzzling for over a month now. No one saw this coming and no one seems to be able to explain what has happened. What we can explain is that his performance is definitely supported (in a bad way) by the underlying metrics. An interesting theory is that for years, pundits observed that Nola was one of the league leaders in called strikes. Maybe Realmuto’s pitch-framing is not helping Nola; maybe the umpires are being less forgiving…or maybe I’m just grasping at straws in trying to explain what’s wrong with the former first-round draft pick. Who knows? What we do know is his pedigree suggests that he should turn it around, but the underlying statistics are not as optimistic. The only solace is that last year after April, the underlying metrics did not see anything positive about Paul Goldschmidt either – and we all know he turned it around. Hopefully, the Philly ace can do the same.

Patrick Corbin, Washington Nationals

After signing a huge offseason contract with the Nationals, the 29-year-old southpaw was being taken as the 13^th SP off the board, due to his phenomenal 2018 campaign where he put up a 1.05 WHIP and 3.15 ERA. Unfortunately, he’s taken a step backward in 2019 with an especially large step backward (over 1.0 standard deviations) in the underlying “stuff” metrics – especially in his chase rate (O Sw%). The numbers are still around league average, so don’t write him off just yet. It is perhaps just a testament to how much of an outlier campaign his 2018 was. Just like what we did above with Matthew Boyd, if you take Patrick Corbin’s 2019 numbers and compare them with pitchers in 2018 who had season stats in the same ballpark as Corbin’s 2019 thus far, we get comps to 2018 Jose Berrios, German Marquez, and Walker Buehler. Not too shabby. Yes, he’s taken a step backward, but really only from the 13^th pitcher to somewhere in the 25^th to 30^th SP range. I’d hold.