This is not quite the rookie season that many envisioned for Matt Moore. He was supposed to be at worst a contender for the rookie of the year, he was supposed to be one of the top pitchers in the league in just his rookie season. He was supposed to be, essentially, the pitching version of Mike Trout this year, maybe to a slightly lesser extent. While the season totals will not look as impressive as hoped before the season started, he has taken massive strides over the past few months and performed at a very high level.
Over his past 15 starts since May 28, Moore has a 2.78 ERA, 90 strikeouts, and 38 walks in 94 innings. Those are rather impressive numbers from a rookie, especially after he posted a 5.07 ERA in his first nine starts of the year. His past six starts have been the most impressive, in which he has gone 4-1 with a 1.38 ERA over 39 innings, with a 39-10 strikeout-to-walk ratio.
So, what has Moore done differently over his past six starts that he was unable to do in his first nine starts? How exactly has he evolved as a pitcher? The biggest difference has been his slider, which has seen massive improvements since the start of the year. The below charts detail his frequency, velocity, strike rate, and whiff rate from the past six starts compared to his first nine starts.
The slider has become his unquestioned secondary offering now, surpassing his two-seam fastball and changeup. Along with the increased frequency, his strike and whiff rates have both risen substantially of late with his breaking ball. Early in the season, Moore was least likely to generate a swing and miss with his slider of any of his pitches, but as the season has advanced it has essentially become his out pitch. With two different fastballs that sit in the mid-90’s, the addition of an impressive slider compared to what essentially acted as a show pitch early in the season has led Moore to a series of dominant outings.
The large drop in velocity from his fastball to his slider gives the pitch more of a slurve feel than a traditional slider. Normally, at his velocity he would be throwing his slider at around 86-88 miles per hour on average, but he sits at around 82 miles per hour with the pitch, which is between where a normal slider and curveball would sit given his fastball velocity. The below .gif shows Moore throwing a slider that has more of a slurve feel than a hard biting slider to strikeout Mark Trumbo in his most recent outing.
Regardless of why Moore was throwing his slider less frequently earlier in the year, whether it be A general lack of feel for the pitch or an organizational decision, making it his most frequently used secondary offering has been a decision that has paid immediate dividends. His strike rates on all of his pitches are up significantly over his past six starts, which may show that he is getting his overall command problems under control. Limiting walks will always be the big focus for Moore, so his ability to command all of his pitches is likely even more important than the increased slider use. However, the increased frequency and ability to miss bats with his slider has elevated him to this level over the past month.
Following the continued development of his breaking ball over his remaining starts will certainly be interesting. With how effective the pitch has been of late, it will be intriguing to see if he and the Rays’ staff have him ramp up his slider usage even more down the stretch. It is easy to fall in love with a nice and easy 94 mile per hour fastball with tailing action, but what has surprisingly been the key to Moore’s development has been a slow slider that has turned into arguably his top offering. While Moore does not have a very expansive repertoire, his ability to evolve as a pitcher in his rookie season has been crucial to both his and the Rays success. His season stats will not look as impressive as anticipated, but his development over the course of the season shows that Moore can certainly be one of the top pitchers in baseball in the very near future.
Ben has been at RotoGraphs since 2012 and focuses most of his fantasy baseball attention toward dynasty and keeper leagues.