Last 30 Day Starting Pitcher Strikeout Rate Surgers — Jul 21, 2021

Pitchers sometimes change rapidly. Whether it’s gaining or losing velocity, altering their pitch mix, changing their delivery, moving on the rubber, or something else, it’s important to pay attention to trends in their underlying skills as it could be very telling. So let’s review the strikeout rate surgers over the last 30 days compared to what these pitchers posted for the season heading into this period.

First off, it’s pretty crazy to find that three of the six names are members of the Rockies rotation. In only one case though, their home/away game split possibility had something to do with it, as you’ll see below for each pitcher.

During Jon Gray pre-last 30 day period, two-thirds of his games started came at home. In his last 30 day period, 40% of his five games started came at home. That’s a big difference, especially when considering how hitter friendly Coors Field is. Don’t forget, Coors Field also reduces strikeouts, though not nearly to a degree that would fully explain Gray’s last 30 day jump. One obvious explanation is that Gray’s fastball velocity has jumped. Early on, he averaged 94.6 MPH with the pitch, but has revved that up to 95.4 MPH over the last 30 days. Actually, the jump began one start before the last 30 day window, when he averaged 95.7 MPH on June 4. That’s interesting timing as after that start, he missed some time due to an elbow injury, and then he was throwing his hardest of the season after returning. He has also managed to post a string of SwStk% marks of at least 13.2% in five straight games that coincide with this last 30 day period. Last year was a disaster thanks to a velocity decline and shoulder injury, but it looks like the good Gray is finally back. It’s always difficult to trust a Rockies pitcher, but there was a time when he was the only one worth rostering.

Unlike Gray, Kyle Freeland has actually pitched a higher percentage of his games at home during the last 30 days than previously. A velocity increase isn’t the answer either. What has changed, though, is increased usage of his slider, which has generated the highest SwStk% of any of his pitches this year. Of course, if you look at the SwStk% marks of all his pitches, even sitting with the highest mark doesn’t make the slider impressive. The pitch has only generated an 11.9% mark, which is weak when it represents the highest mark of a pitcher’s repertoire. This strikeout rate spike merely brings Freeland’s season mark back up to where it’s sat the last couple of seasons and just below his career average. His SwStk% remains poor, he has lost his ground ball ability, and his control is just average. I don’t think you’re counting on him as a fantasy asset on your team, so this is just a reminder to continue avoiding him, as the increase in slider usage isn’t enough in my mind to turn him back into a usable starter.

It’s been a major disappointing season for Kenta Maeda, who missed a couple of weeks due to a strained adductor. Earlier in the season, Maeda’s strikeout rate had fallen to a career low, so this last 30 day surge has really rescued his season mark, pushing it closer to his career average. Interestingly, it doesn’t appear to be explained by any sort of significant pitch mix change or increased fastball velocity. He has simply gotten better results from what he had been doing all along, as his SwStk% has jumped to 15.4% over the last 30 days versus a 13% mark previously. It’s a good reminder that with no obvious change, typically veteran pitchers will eventually rebound and get back to the underlying rates we expect from them.

Sean Manaea has been a strikeout machine these last 30 days, which is rarely an apt description for the southpaw. His pitch mix has really jumped around during each start, so there’s no consistent trend of any changes that have occurred over the last 30 days. What has changed though is his fastball velocity that has risen from 91.7 MPH to 92.6 MPH over the last 30 days. That’s a pretty meaningful jump, especially for someone who doesn’t throw that hard to begin with. It has fueled a spike in SwStk% from 11.6% to 14%, which pairs really well with his consistently strong walk rate. That fastball velocity is now at its highest season mark since his 2016 debut. It’s hard to believe this is the same pitcher who had seen his velocity dip just below 90 MPH back in 2019. Given this newfound velocity, he’s pretty clearly a new pitcher and his preseason expectations need to be adjusted upward.

German Marquez is the third Rockies pitcher on this list, but has only made four starts during his 30 days period, half of which came at home. His pitch mix has been altered, as he has upped the usage of his slider pretty significantly, at the expense of both his four-seamer and curveball. What’s incredible is that Marquez boasts two pitches with a SwStk% above 20%, not only this year, but for his career. Those two pitches are the slider and curveball, so it seems to hardly matter whether he opts for one over the other. The big difference is being less reliant on the fastball though, so throwing one of those two non-fastballs more often is helping to drive up that strikeout rate. There hasn’t been an uptick in velocity over the 30 day period, but his velocity was actually down in his first two starts of the period, before surging in his last two starts. Marquez has shown serious strikeout ability before, so he should continue to earn value, even calling Coors Field home, just like Gray.

Alec Mills is a surprise name on this list and certainly an actionable one as he likely sits on free agency in many leagues given his 4.64 ERA. Mills is an extreme ground ball pitcher with mediocre strikeout and walk rates, so any strikeout rate surge is going to push him into intriguing territory. He has actually only made seven starts all season, five of which have come over the last 30 days. You don’t normally see a pitcher’s strikeout rate jump after moving into the rotation! Not a whole lot has changed with his pitch mix and velocity, though it does qualify as good news that he hasn’t lost any velocity as he has started games. It’s hard to buy into that strikeout rate spike though given an underwhelming 7.2% SwStk% during the period, but he has induced a high rate of called strikes, so that has helped keep his strikeout rate above 20%. Overall, this is an interesting skill set, but I am always hesitant to recommend a pitcher who owns such a lackluster SwStk%. It gives the pitcher little margin for error, with the potential of one of those two inning, 9 hit, seven run implosions always a possibility.