Welcome to our surprising starts series. Every week we’ll be going over a few surprising starting pitcher performances around the majors to determine whether these starts were smoke and mirrors or something more.

This week we're looking at the two top pitching prospects from 2016, as well as a pitching prospect from 2013 that failed to launch the first four times he was given a chance.

Former number two pitching prospect Tyler Glasnow dazzled over three innings on Wendesday against the Angels, while former number one pitching prospect Lucas Giolito shut down Glasnow Rays on Friday. Robbie Erlin is on about his fifth chance in the Padres rotation, but may have staying power this time around.

Real Deal or Mirage?

Tyler Glasnow, Tampa Bay Rays

2018 Stats (in Pittsburgh’s bullpen): 56 IP, 4.34 ERA, 3.64 ERA, 2.1 K/BB

08/01 vs. LAA: 3 IP, 2 H, 1 ER, 1 BB, 5 K

This was a Rays-esque start, with Glasnow only going three innings and Jacob Faria piggybacking him for 3.2 after Glasnow was removed. However, the Rays say they intend to use Glasnow as a traditional starter. He still needs to be stretched out since he was working out of the bullpen in Pittsburgh which is why this start only went three innings. Even though Glasnow’s 4.34 ERA was high for a reliever he was getting much better results out of the pen then as a starter. In 18 career starts Glasnow has been a disaster, with a 7.07 ERA, 1.89 HR/9, and 1.61 K/BB ratio. The underlying numbers out of the bullpen were much better than his 4.34 ERA, as Glasnow had a 30.3% strikeout rate and 56.8% groundball rate. A 17.1% HR/FB rate is only 1% lower than it was last season, yet his HR/9 fell from 1.89 to 0.92 because of the groundball rate. Glasnow’s 3.37 xFIP and 3.54 SIERA are both improvements by over two runs from the season before, when Glasnow had a 5.64 xFIP and 5.62 SIERA. His 13.8% walk rate was still atrocious, but at least he wasn’t getting hammered.

Glasnow has simplified his arsenal this season, ditching his two-seamer and changeup to rely mainly on his fastball and curveball with the occasional slider. The sinker had to go. It wasn’t a pitch he used as a prospect and began implementing it in 2017, where it promptly got crushed for a .422 AVG and .241 ISO. The changeup was Glasnow’s weakest offering besides the sinker, and in transitioning to the bullpen he no longer had a need for the pitch. He didn’t throw it in this outing against the Angels, but he might use it if he goes a full second time through the order or faces a lefty-heavy lineup.

This approach has helped Glasnow’s fastball perform better this season, as batters are hitting just .242 with a .148 ISO against the pitch this season, nearly a 100 point drop in both metrics. He is also averaging 97.5 MPH with the pitch, and even touched 99 in this start against the Angels. This isn’t a Nathan Eovaldi 97 either, Glasnow has wicked late movement on the pitch. Here is his best fastball from this start.

No chance for Justin Upton. Just no chance. It remains to be seen whether Glasnow can do that regularly as a starter, but he sure looked good in this outing.

His curveball has always been Glasnow’s best and most consistent offering. Even when Glasnow was at his worst last year his curveball performed well, and this year is no exception as batters have a 17.5% whiff rate and .217 AVG against the pitch. There is a discrepancy between pitch tracking website in regards to how often Glasnow is using his curveball this season. Brooksbaseball.net and PitchF/x say he’s using his curveball 25% of the time and hardly throwing his slider. Statcast disagrees, and says Glasnow is using the curveball 17% of the time and throwing his slider 9% of the time. After reviewing the game it looks like Statcast got this one right, and PitchF/x is mistaking Glasnow’s slider for a curveball. PitchF/x says he didn’t throw a slider in this start, but he threw multiple sliders. Here is an example of a slider.

And here’s a curveball for comparison.

The pitches have similar spin rates around 2800 and both are breaking balls, so it’s easy to see how an automated tracking system may not differentiate between them properly, but he is using both a slider and curveball effectively.

Glasnow’s slider has been amazing for him this season, with batters hitting just .069 with a .093 xBA and .030 xwOBA. He’s only thrown 101 sliders, but those xStats are something special. The slide could just replace the changeup as Glasnow’s third pitch, which could be the catalyst for a breakout down the line. His curveball is unquestionably effective, he is throwing with more velocity, and he’s potentially added a second plus breaking ball to his repertoire. Walks will likely continue to be an issue for him, but he looks good in every other aspect. The former top two pitching prospect is worth a shot down the stretch in redraft leagues, and this trade to Tampa Bay helps his dynasty value.

Verdict:

Glasnow needs to be stretched out, but the addition of a slider and increase in fastball velocity have allowed him to pitch better than ever. Walks are an issue, but he’s at least corrected his home run and hard contact problems from 2017. Ditching the sinker and changeup for the slider might be the move Glasnow needed to find success as a starter. We’ll have to see if the velocity gains hold as he goes deeper into games, but he’s a good player to add at least as a speculative bench player. If things go right for Glasnow could pop big time. This was only three innings, but the upside is too rich to ignore.

 
Lucas Giolito, Chicago White Sox

2018 Stats (prior to this start): 113.2 IP, 6.26 ERA, 6.10 FIP, 1.1 K/BB ratio

08/03 @ TB: 7 IP, 2 H, 1 ER, 3 BB, 6 K

What the White Sox were doing to Giolito this season was almost inhumanely cruel. He clearly hadn’t been ready for the majors, yet they've been trotting him out there every fifth day like a cattle being led to slaughter. By many metrics Giolito has been the worst starting pitching in baseball. Among qualified starters he has the second highest ERA (5.97) and the highest FIP, xFIP, and SIERA, all barely south of six. He also has the highest walk rate (12.6%), second worst strikeout rate (14.3%), and second worst chase rate (25%). He did everything besides spontaneously burst into flames on the mound during a game. Actually, that may have happened at some point for all we know, but there were no witnesses because nobody watches White Sox games.

Things have been going better for Giolito as of late, as he’s notched quality starts in five of his last seven outings. The non-quality starts were disasters in which Giolito allowed 12 earned runs in 9.1 innings, but a good stretch by Giolito’s standards nonetheless. During this stretch Giolito has changed his pitch mix, featuring his 94 MPH four-seamer less and using his changeup and two-seamer more often. Since June 28, when Giolito’s hot stretch began his changeup gained nearly three inches of horizontal movement. His fastball also gained an extra mile per hour of velocity. This has led to a 4% increase in soft contact and 8% increase in groundball rate over Giolito’s past seven starts. This is a step in the right direction for Giolito, as batters have hit .192 with a .115 ISO against his changeup over his last seven starts, compared to a .297 AVG and .135 ISO before that.

It’s not all sunshine and roses for Giolito, however. During his seven start stretch he still has a 5.58 FIP and 1.4 K/BB ratio, making him nowhere near usable in a standard mixed league even as a streamer in the easiest of matchups He’s been riding a .218 BABIP and 80% strand rate to a barely passable 4.04 ERA and 1.28 in these 42.1 innings. There is no margin for error in this pitching style, and considering the White Sox defense has collectively combined for -45 DRS  Giolito is getting no help behind him. Giolito’s fortunes turning around are just that, good fortune. This is reminiscent of Matt Harvey’s lucky streak with the Reds. All the peripherals are still terrible, but he’s gotten lucky for about a month now.

Verdict:

Slight changes in pitch mix have lead to incremental improvements with Giolito’s changeup and fastball, but there is a lot more bad than good in this profile. His success is solely dependent on his BABIP, and just because the ball has fallen in his favor more often than not recently doesn't mean it's sustainable. With the fantasy baseball season entering crunch time let’s not spin this roulette wheel.

 
Robbie Erlin, San Diego Padres

2018 Stats (prior to this start, primarily out of bullpen): 59.2 IP, 3.47 ERA, 3.32 FIP, 8.3 K/BB ratio

08/02 @ CHC: 5 IP, 2 H, 1 ER, 1 BB, 4 K

Erlin had quietly been great out of the bullpen for San Diego, but his two spot starts prior to this game went terribly. He gave up a combined 12 runs (11 earned) in seven innings against the Dodgers and Nationals. While the matchup didn’t get any easier in this game, Erlin held the Cubs to one run and got his second win of the season. Erlin has been bouncing in and out of the Padres’ rotation since 2013, but a torn UCL in 2016 cost him all of last year and put him in the bullpen for the foreseeable future. The benefit of being on a team that has been rebuilding for the past five years means plenty of opportunities, and this may be Erlin’s last chance to prove himself as a starter in the majors.

He uses a four pitch mix, including a 90.8 MPH four-seamer, a 90.7 MPH sinker, an 84.5 MPH changeup, and 76.8 MPH curveball. The curveball has been amazing for Erlin, with batters hitting just .140 against the pitch with an .040 ISO and a 76.7% groundball rate. His sinker and changeup both have groundball rates above 57% as well. His four-seam fastball is a pop-up machine, with a 55% flyball rate and 26% infield flyball rate. Erlin may only have a 7.5 K/9, but he seems to have this contact management thing figured out.

He has also consistently underperformed based on ERA predictive metrics. Erlin has a career 4.18 ERA, but a career 3.62 FIP and 3.72 SIERA. That’s because he has consistently displayed the ability to limit walks and home runs. He has had excellent control throughout his minor league career and his career walk rate in the majors is 4.9%. His 2.9% walk rate this year is the best in the majors among pitchers that have thrown at least 50 innings. Erlin has also done a good job at suppressing the long ball, and that’s because of his ability to induce groundballs and infield flyballs. He has a career .409 xSLG and 0.97 HR/9, and his 3.20 xFIP this season suggests Erlin’s home run suppression is legitimate. Sure, playing home games in Petco Park helps, but it’s not like he’s going anywhere.

Verdict:

Is Erlin the next Chris Sale in waiting? No, but he’s a serviceable streamer, especially at home. Even though he has a low strikeout rate he makes up for it with good contact management as well as walk and home run suppression. He does have a 4.84 ERA as a starter compared to a 2.51 ERA as a reliever, but his 3.84 FIP as a starter means he should be a solid if unspectacular matchup-dependent option.

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