Are You For Real? Surprising Pitcher Starts From Bryan Woo and Julio Teheran

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.

We are looking at two pitchers with very different styles who've taken different paths to the majors this season. First, we'll look at Bryan Woo's nine strikeout performance Friday against the White Sox. Then, we'll take a peek under the hood at Julio Teheran's latest strong outing, a one-run affair against Pittsburgh.

Roster percentages are taken from Yahoo and are accurate as of 06/19/2023.

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Bryan Woo, Seattle Mariners

9% Rostered

2023 Stats (AA): 44 IP, 2.05 ERA, 2.78 FIP, 27.3% K-BB%
6/16 vs. CWS: 5.2 IP, 3 H, 2 ER, 0 BB, 9 K

Woo had the best start of his young career on Friday, carving up the White Sox for nine strikeouts over 5.2 innings. Woo may’ve fallen one out short of his first career quality start, but this looks like a huge step in the right direction after a rocky debut. Woo has plenty of talent as one of Seattle’s top pitching prospects. Will he Falter like Bailey, or will Bryan have fantasy players shouting Woo?

Originally a sixth-round pick out of Cal Poly Tech, Woo had a rocky college career, posting a 6.36 ERA in 69.1 innings, primarily as a reliever. Adding injury to insult, Woo suffered a UCL tear and underwent Tommy John surgery towards the end of his college career. None of that deterred Seattle from taking a chance on Woo, and after Friday’s performance, it’s easy to see why they rolled the dice. Working with a four-pitch mix, Woo is best known for his fastballs. He throws a four-seam and two-seam fastball, both averaging 95.3 MPH and 95.4 MPH on the gun respectively. Alongside the fastball, Woo uses a slider and the occasional changeup as secondary pitches.

It was mostly about fastballs in this start for Woo, who threw either his four-seamer or two-seamer 75% of the time. The whiffs piled up as well, with Woo notching 12 of his 19 total whiffs with heaters. Opposing batters have struggled to hit Woo’s four-seamer through his first three starts, with Woo posting a .208 AVG and .310 wOBA. Statcast paints an even rosier picture, with opponents mustering a mere .158 xBA, .301 xSLG, and .233 xwOBA off the pitch.

What makes Woo’s fastball so special? In addition to plus velocity, Woo also has above-average horizontal movement with the pitch, which breaks in on righties and away from lefties, increasing its deceptive capabilities. This is especially true on high fastballs, an area of the zone Woo has targeted heavily throughout his first three starts. Here’s a look at Woo’s four-seamer heatmap through his first three starts (top), along with a heatmap of fastball whiff rate (bottom) based on pitch location.

Not only are hitters deceived by the illusion that a high fastball rises as it approaches the plate, but they must also contend with the plus velocity and movement of Woo’s four-seamer, leading to big strikeout days on the mound like we saw Friday.

While Woo’s fastball did plenty of heavy lifting in this start, this outing was also the most prominently we’ve seen Woo use his slider thus far. Woo threw 22 sliders in this game after throwing 24 combined sliders in his previous two starts. He also had a monster 54% whiff rate with the pitch, his highest mark in any start thus far. A bendy 83 MPH offering, Woo’s slider boasts above-average break and drop, making it an ideal secondary pitch for his fastball-heavy style. Here’s an example of the pitch from this start.

Jake Burger's strikeout probability quickly went from 39% to 100% as that beauty left Woo's hand. It’s easy to see how Woo was putting up such gaudy strikeout numbers in the minors, and based on stuff alone he should be able to replicate this in the major leagues.

Does that mean it’s time to break open the FAB piggy bank and throw all your chips on Woo? Not quite. The raw stuff looks amazing, but the stuff is just that: raw. Woo was all over the place with his slider in this one, which wasn’t exactly a deviation from previous starts. Here’s a look at Woo’s pitch location during this start.

There are quite a few orange triangles towards the top or middle of the zone, AKA hanging sliders. When the pitch is good, it’s good. But when it’s bad, look out below. This may be the reason that, despite a 38.5% whiff rate and .231 AVG against the slider overall, Woo has allowed a .538 SLG with the pitch.

Fantasy players should be skeptical of Woo’s long-term sustainability based on this one start. Not only is one start an insufficient sample on its own, but Woo’s opponent played perfectly into his strengths. The White Sox have been one of the least effective offenses against right-handed pitchers this season, posting a collective 81 wRC+, .289 wOBA, and an MLB-worst 0.28 K/BB ratio. Furthermore, the White Sox started just two left-handed batters in this game, Andrew Benintendi and Gavin Sheets, both of whom homered off Woo.

As raw as Woo’s slider is, his changeup may well not exist. You can count the number of changeups Woo has thrown this season on one hand (Hint: use your thumb). Without a workable changeup or alternative secondary pitch, Woo will either need to fool lefties with a slider he routinely misses on, or he’ll need to get them out with just fastballs, both of which are not viable long-term solutions for an MLB starter. Woo can improve and overcome these issues, but it’s not going to happen overnight. He’s got a bumpy road of development ahead. We’ll see starts as we did on Friday, but we’ll also see starts like Woo’s MLB debut, where the powerhouse Texas Rangers (118 wRC+ vs. R) rocked him for six earned runs in two innings.

Verdict:

With two above-average fastballs and a slider that can generate whiffs, Woo’s got the stuff to impress. He’s been able to rack up big strikeout numbers at every level thanks to his combination of hard, deceptive fastballs and gravity-defying sliders. On a pitch-by-pitch basis, Woo still misses his spots more than he should, which could make him prone to surrendering more extra-base hits than he probably should.

He lacks an effective off-speed pitch to handle left-handed hitters, so Woo could carry large platoon splits while he works to develop his changeup and his command. There’s a lot of talent here, but the matchup will play a big role in whether one should deploy him. When considering whether to start Woo, players should avoid teams that excel against right-handed pitchers and/or use a lineup with lots of left-handed hitters.

Julio Teheran, Milwaukee Brewers

44% Rostered

2023 Stats (prior to this start): 24.1 IP, 1.48 ERA, 3.52 FIP, 14.4% K-BB%
6/16 vs. PIT: 6 IP, 1 H, 2 ER, 1 BB, 4 K

I’ve heard the term “fantasy zombie” thrown around in the past, and I think that’s an apt description of Julio Teheran’s 2023 season thus far. It has been years since fantasy players thought of Teheran as anything more than a punching bag for their DFS lineups. Once a fixture in the Atlanta Braves rotation, control issues and an inability to adapt to the juiced ball/launch angle era caught up to Teheran, who spent 2022 bouncing around various independent teams.

Prior to his arrival in Milwaukee, Teheran had a 5.63 ERA in eight starts for the El Paso Chihuahuas, the Padres Triple-A affiliate. Despite getting knocked around in Triple-A, Teheran owns a sparkling 1.78 ERA through five major league starts. Is Teheran here to stay, or are the good times poised to end?

During his time with Atlanta, Teheran relied primarily on his four-seamer and slider, but this season he’s pivoted to being a sinker-cutter pitcher. Teheran has thrown either his four-seam fastball or slider a combined 23.7% this season, a stark contrast to his 62.7% combined career usage rate of these pitches. Could it really be this simple?

The MLB world thought Teheran’s arm was fried prior to this season, and usually a shift toward cutters and sinkers is a signal of desperation for a pitcher. Instead of rescuing careers, this “junk ball” style often hammers the final nail in the coffin of a mid-rotation starter’s career. Is Teheran the exception?

The most interesting aspect of Teheran’s success has got to be his cutter, which is an entirely new pitch for him. Coming in at 85.5 MPH, the pitch is harder and has much less break than his slider. Batters have struggled against Teheran’s cutter thus far, posting a .200 AVG, .250 SLG, and .219 wOBA off the pitch. Teheran isn’t generating many whiffs with the pitch considering his meager 8.3% swinging strike rate with it, but he is generating poor contact. Amusingly, the pitch velocity is perfectly symmetrical both ways. Teheran throws it in at 85.5 MPH, and batters send it back with an 85.5 MPH average exit velocity.

Not only are batters hitting it weakly, but they’re also hitting it straight in the air. Teheran has a 35-degree average launch angle, a 41.7% infield flyball rate, and a 63.2% overall flyball rate with the pitch thus far. Flyballs may be the most likely batted ball type to become a home run, but they are also the least likely batted ball type to fall for a hit in general. Teheran’s .211 BABIP with his cutter may be a little fortunate, but his low BABIP wasn’t all luck either. Teheran earned his low BABIP by forcing hitters into weak contact. Teheran has a .267 career BABIP, so forcing bad contact is sort of his specialty, and he’s been doing it wonderfully with his cutter thus far.

Now, to the other piece of the Teheran equation, his sinker. During his heyday with Atlanta, Teheran’s sinker was secondary to his four-seam fastball. He lived and died (and really, really died) by the four-seamer. That’s not the case anymore, as Teheran’s sinker is his most frequently used pitch. He has thrown his sinker 37.4% of the time this season, nearly double his career usage rate. Batters have struggled to square this one up as well, with opponents hitting just .240 with a .340 SLG and .268 wOBA off the sinker.

Sinkers are known for their propensity to induce groundballs, and that’s certainly been the case for Teheran. Opponents have a 58.5% groundball rate and a 4-degree average launch angle off Teheran’s sinker. Longballs were a big problem for Teheran during his prime years, which is why his current 41.2% groundball rate and 0.89 HR/9 (both would be career bests if sustained) are so encouraging.

While there is plenty to like about what Teheran has done thus far, it shouldn’t be surprising to hear that luck has contributed to his newfound success. When evaluating a pitcher’s fortune, there are three simple stats that can reveal quite a bit: BABIP against, strand rate, and HR/FB. Pitchers have some influence on these numbers, as demonstrated by Teheran himself, but for the most part, pitchers will gravitate toward the league average over an extended period.

There’s only so much influence a pitcher can have over the randomness of a ball in play. There's a reason that strikeouts, walks, and home runs are considered the three true outcomes. For Teheran, a .220 BABIP, 87.2% strand rate, and 7.9% HR/FB ratio all suggest that lady luck has been on his side. Not only are all three numbers far from the league average, but they’re also far from Teheran’s career average as well. Even with a pitching style that emphasizes weak contact, it would be hard to maintain these numbers long-term.

Where does that leave us? His most pessimistic ERA estimator, xFIP, has him at 4.43. That sounds bad when compared to his 1.78 ERA, but a 4.43 xFIP is quite an improvement for Teheran considering he had a 5.06 xFIP between 2017-2021. Still, even if 4.43 is an improvement, on its face it’s not an inspiring outlook for his fantasy upside. A large disparity in ERA and xFIP might be a big red flag for many pitchers, but because Teheran’s pitching style relies on weak contact and low strikeouts, fielding-independent metrics like FIP and xFIP often paint a gloomier picture of the pitcher’s future than what’s actually ahead.

These metrics shouldn’t be totally discounted in the case of Teheran, but Teheran is reminiscent of former Toronto righty Marco Estrada, whose focus on inducing weak contact often left him with solid surface stats, but bloated peripheral metrics. Pitchers like this aren’t sexy and don't feel all that secure on a start-by-start basis, but they can produce results.

Verdict:

This may shock some, but Julio Teheran is not the second coming of Sandy Koufax, and his 1.78 ERA will rise over time. Even if he’s overperforming, Teheran’s transition to becoming a sinker-cutter pitcher may help resurrect his career. His cutter has replaced a volatile slider, allowing him to consistently generate weak contact with a secondary pitch. He’s reduced his home run rate by using his sinker as his primary fastball, giving him a reliable groundball pitch that helps him get out of the inevitable jams he’ll find himself in, as does any pitch-to-contact pitcher.

It was easy to dismiss Teheran’s success at first (I mean, the entire MLB had dismissed him at one point), but there is some staying power here. Teheran has gone from a complete afterthought to a streamable veteran. Teheran hasn’t earned my trust against all matchups yet, but he’s fine to slide in against a weak or average opponent.

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