Are You For Real? Surprising Pitcher Starts From Michael Kopech and Reid Detmers

Welcome back to "Are You For Real?", a weekly column where we take starting pitchers who had surprisingly good starts over the past week and put them under the microscope to determine whether they're legit or just smoke and mirrors.

The post-hype pitchers came out to play last weekend, giving us some interesting pitching performances to break down. First, we'll look at arguably the best start of Michael Kopech's career as he held Kansas City to a lone baserunner in an eight-inning gem. Then, we'll break down a 12-strikeout performance from Angels southpaw Reid Detmers against the Twins on Friday.

Roster percentages are taken from Yahoo and are accurate as of 05/22/2023.

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Michael Kopech, Chicago White Sox – 25% Rostered

2023 Stats (prior to this start): 42.1 IP, 5.74 ERA, 7.32 FIP, 6.8% K-BB%

05/19 vs. KC: 8 IP, 1 H, 0 ER, 0 BB, 10 K

Kopech was incredible on Friday, carrying a perfect game bid into the sixth inning before finally allowing a baserunner. That runner would be the only one to reach base against Kopech, who finished the evening with 10 strikeouts over 8 scoreless innings. Not only was this Kopech’s best start of the season, it may be the best performance of his career to date. There were high expectations for Kopech as a prospect, leaving many wondering if the flashy fireballer could be finally putting things together.

Originally a first-round pick by the Red Sox back in 2014, Kopech was a key piece in the Chris Sale swap. The hype for Kopech as a prospect was palpable. The main reason for the excitement? Heat. Kopech was routinely touching 100 MPH on radar guns and even recorded a 105-MPH pitch as a minor leaguer. Scouts were salivating over Kopech’s potential, thinking that he’d become a frontline starter by pairing his high velocity with a wicked slider and plus curve. Injuries and inconsistencies have prevented that from happening, and Kopech rarely reaches triple digits on the gun anymore. Still, this start was the first step in the right direction.

It was all about the fastball for Kopech as a prospect, and it was all about the fastball in this start as well. Kopech threw his fastball 70% of the time in this start, even higher than his 63.4% usage rate on the season. Despite colossal struggles at times, Kopech’s fastball has remained effective. Opponents are hitting just .223 off the pitch this season with an 11.7% swinging strike rate, impressive numbers considering Kopech is the owner of a 6.28 FIP. Kopech no longer possesses elite velocity, but his average of 95.7 MPH is still well above average for a starter. Kopech also has 95th-percentile spin and above-average movement, making the fastball a powerful weapon.

Kopech’s fastball is still his standout pitch, but it’s not without its flaws. Rather, Kopech is not without his flaws. Batters may only have a .223 AVG against Kopech’s heater, but they have a .466 SLG and .461 xSLG. Kopech has surrendered seven home runs with the pitch already, making it a big contributing factor to his ugly 2.15 HR/9 rate. What’s the cause of this gopheritis? Two things: flyball tendencies and poor control.

Kopech currently has a 33.3% groundball rate, which is the ninth-lowest among qualified starters. His fastball drives the low groundball rate, as it’s his most frequently thrown pitch, and has a 49.3% flyball rate, the highest of any pitch for Kopech. A pitcher with flyball tendencies is already playing with fire at Guaranteed Rate Field, but Kopech’s poor control exacerbates the issue. A big focus of Kopech’s approach is the high fastball, which can be an incredibly effective pitch for Kopech but can also get him in trouble when he fails to execute. Here’s a look at Kopech’s fastball heatmap from this season (via brooksbaseball.net).

He’s focused on keeping the ball up but lives a little too much in the zone. To get an idea of how this affects him, here’s a look at an isolated power heatmap for Kopech’s fastball this season.

Batters can’t catch up to Kopech’s fastball when he locates high, but opponents have been feasting on anything in the zone, especially anything in the middle or lower parts of the zone. Kopech may’ve walked zero batters in this one, but it was the first time all season that he allowed zero walks. In fact, he issued six free passes in the start prior to this one and has issued multiple walks in all but two starts this season. Furthermore, the Royals have a 6.5% walk rate against right-handed pitching this season, tied for the lowest in the league. This most recent start was an encouraging sign for Kopech’s control, but we’ll have to see him continue the trend before we can trust him.

After the fastball, Kopech’s most used pitch is the slider, which he’s thrown 25.6% of the time this season. Opponents have struggled to get base hits off the pitch with a  .237 AVG against, but have had no problem hitting the pitch for power. Batters have a .475 SLG and .587 xSLG off Kopech’s slider. Like his fastball, Kopech’s slider has strong flyball tendencies, with 47.8% of all batted balls off the slider ending up in the air. With average movement and velocity, Kopech doesn’t rack up exceptional strikeout numbers with his slider. He has a 10.4% swinging strike rate and a 30.2% chase rate with his slider this season, both unremarkable numbers.

Kopech did have five whiffs with the pitch in this start, but those results may reflect the opponent rather than the pitcher. The Royals have a 25.1% strikeout rate against right-handed pitching this season, tied for second-highest in the majors. Much like with Kopech’s control, we need to see him do it more consistently and against stronger opponents before we can believe it.

Verdict:

Kopech is coming off the best start of his career, and there are plenty of positives to take away from this outing. This is some of the best control we’ve ever seen from Kopech, and it’s one of the few times we’ve witnessed his strikeout potential with the fastball-slider combo. Kopech’s fastball isn’t the 105-MPH stuff of legend we remembered hearing about, but it’s still a plus pitch that he can have success with if the rest of his game comes together.

Before we can start trusting him, Kopech will need to show us a few more strong outings. The Royals have a pitiful 74 wRC+ against right-handed pitchers this season, and Kopech has floundered against better opponents so far. Keep an eye on him, and maybe add him in deeper leagues, but refrain from using him in your starting lineups until we see more.

Reid Detmers, Los Angeles Angels – 39% Rostered

2023 Stats (prior to this start): 35 IP, 4.89 ERA, 3.90 FIP, 17.3% K-BB%

05/19 vs. MIN: 5.2 IP, 2 H, 3 ER, 3 BB, 12 K

Detmers was a strikeout machine on Friday, tying a career-high by striking out 12 batters in a no-decision against the Twins. Strikeouts have been one of Detmers’s strong points this season, as the 23-year-old southpaw has a stellar 11.73 K/9 on the year. That strikeout upside certainly has piqued the interest of fantasy players, but Detmers still owns an ugly 4.87 ERA and 1.43 WHIP following this start. Was this start a righting of the ship, or is it still rough seas ahead for Detmers?

Originally the 10^th overall pick back in 2020, Detmers was one of the Angels’ most highly touted pitching prospects. His deep repertoire with a plus fastball and two strong breaking balls had scouts excited about Detmers's long-term potential as a starter. Altogether, Detmers works with a four-pitch mix consisting of a four-seam fastball, slider, curveball, and the occasional changeup. The slider was the main attraction for Detmers in this start, as he racked up 17 whiffs with his slider alone.

17 whiffs is a great number for a start in general, making it even more impressive that Detmers achieved this number with just one pitch. If he was going to do it with any pitch it’d be the slider, which has been Detmers best strikeout pitch this season. Opponents are hitting .250 against the pitch with a monster 24.1% swinging strike rate and 42.3% chase rate. The strikeout numbers are way up on the pitch this season.

hisThe reason? Detmers has been a big spike in slider velocity, averaging 90.4 MPH with the pitch this year compared to 86 MPH last season. More’s changed than the velocity as well. Detmers’s slider went from a sweeping, loopy pitch to a harder, sharper version. The pitch is closer to a slider-cutter hybrid (slutter) than its previous iteration, which was closer to a curveball. To get a sense of the difference, let’s look at a Detmers slider from last season (top) compared to this season (bottom).

2022:

2023:

It’s essentially a different pitch, which has unlocked a new level of strikeout prowess for the left-hander. With such good strikeout metrics, it’s surprising that opponents have even managed to hit .250 off the pitch. Opposing batters have been fortunate enough to have a .408 BABIP off Detmers’s slider this season thanks to an inordinate 38% line drive rate. Detmers had a 23.1% line drive rate and .314 BABIP with his slider last season, so I think this may be a case of misfortune, even considering his tweaks to the pitch.

While we’re getting a little granular by looking at these numbers just on his slider, if we zoom out we can see similar bad luck. Detmers’s .366 BABIP against is the fourth-highest in the majors, and his 61.4% LOB rate is the seventh-lowest (min. 40 IP).  Detmers might have a 4.87 ERA, but his 3.45 FIP, 3.81 xFIP, and 3.70 SIERA all suggest he’s pitched much better.

While a lot of his poor performance can be boiled down to bad luck, not all of it can be excused away. Efficiency has been an issue for Detmers, as he’s only managed to complete six innings once all season. Walks have been an issue as well since Detmers has a bloated 9.6% walk rate this season and has yet to appear in a game without issuing at least one walk. Detmers’s command hasn’t matured to the level we’d like to see yet, making him volatile on a start-by-start basis and limiting his greater impact by driving up his pitch count and causing early exits.

His fastball has been clobbered this season, to the tune of a .298 AVG, .447 SLG, and .388 wOBA. Bad luck? Hardly, as Statcast projections suggest that Detmers’s fastball has overperformed on expected outcomes this season. He has a .330 xBA, .532 xSLG, and .427xwOBA with his fastball this season, numbers that are all about 70 points higher compared to last season.

Detmers has added nearly 2 MPH to his fastball this season, but the pitch has poor spin and movement, meaning Detmers really can’t afford to miss his spots. As his command improves his fastball performance should improve, but we shouldn’t expect that to happen overnight, or even this season. While not skyrocketing to success, Detmers has been following a solid path of progression throughout his young career, and there’s plenty more room to improve for this talented young arm.

Verdict:

Detmers has undergone a couple of changes this season. He’s throwing a few MPH harder, and he’s begun featuring a harder, sharper slider more prominently, leading to a big spike in strikeout numbers. While that hasn’t directly translated to a breakout, much of Detmers’s misfortune can be blamed on just that, misfortune. An elevated BABIP and inordinate strand rate drove up his ERA and WHIP, and ERA estimators suggest better days are ahead for Detmers. Detmers still lacks polish and his command can waver at times, but there is plenty to like about him. He’s worth an add in any league deeper than 12 teams and might be worth a stash in shallower leagues too if the player needs pitching.

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