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What has Changed for Miles Mikolas

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MLB: Washington Nationals at St. Louis Cardinals Jeff Curry-USA TODAY Sports

Miles Mikolas has now been stateside for the last two years and when made his return to the MLB last year and looked like a completely different pitcher, pitching himself to a 2.83 ERA and 3.28 FIP. By the end of the season he had posted 4.2 WAR and was an anchor of the Cardinals rotation as he tossed over 200 innings and average over 6 innings per start. However, that has changed this season as he has lost a lot of the dominance that he demonstrated last year.

Mikolas is still a control artist and he has even slightly improved his K-BB%. However, despite this, he has seen his ERA rise to 4.29, while his FIP has also risen to 4.26. This is largely due to a spike in home runs allowed. The right-hander’s HR/FB% has risen from 9.2 % last season to 16.0% this season. He averages 1.33 home runs allowed per nine innings which is a vast increase from 0.72 last year. Some of this can probably be attributed to the new baseball being used this year as home run numbers have drastically risen across the league. However, it is unlikely that this is the only reason.

One of the factors that could lead to this is a difference in the batted balls allowed by Mikolas this season. His GB% has dropped by 2%, while he has also allowed more flyballs (1.2% increase) and line drives (0.7% increase). Additionally, his quality of contact allowed has also changed significantly. The 31-year-old is allowing significantly more hard contact this season as opposed to last season. He has seen his hard contact percentage rise 8.9% from last year, at the expense of his soft contact percentage (2.9% decrease) and his medium contact percentage (6% decrease). This is the reason why his average exit velocity allowed has risen from 85.4 mph last season to 88 mph this season. When that is combined with a 2.6 degree (7.4 in 2018, 10.0 in 2019) rise in launch angle it makes sense that he has allowed significantly more home runs this season.

Clearly, he is being hit harder this season and that is causing his home run problem. However, now the question becomes what is causing him to be hit harder? This could be due to a significant decrease in slider effectiveness. Last season, 26% of the pitches that Mikolas threw were sliders. This season he is throwing slightly less (23%). However, in 2018 Mikolas allowed hitters to post a 0.201 wOBA against his slider, making it his most effective pitch. That has completely changed this season as it is now his worst pitch in terms of wOBA allowed. He has surrendered a 0.339 wOBA to opposing hitters on this pitch.

This has led to a significant change in batted ball results on the pitch. After yielding just one home run on the pitch last season, the right-hander has conceded eight this year. He is also missing less bats this season, forcing a whiff rate of just 24.2%, a decrease of more than three percent from the prior year (27.6%). The overall lack of effectiveness on this pitch could be linked to his inability to tempt hitters into swinging. He throws it in the strike zone 44% of the time and the highest percentage of his sliders end low and outside to a right-handed hitter. This means that the most common place for him to locate the pitch is out of the strike zone and it is by a wide margin.

This is the heat map for Mikolas’ slider. This is not a bad spot to locate a slider, but if he cannot throw it close enough to the plate to make the opposing hitter want to swing then it loses a lot of its effectiveness.

Last season Mikolas was able to generate a swing on 56% of his sliders. This season, however, he has only made hitters swing at 49.4% of his sliders. This is a big change. When he is unable to consistently throw his slider over the edge of the plate, or at least close to the edge of the plate, he is put at a disadvantage as he is then under more pressure to throw a strike, or generate a swing on a pitch outside the zone on the next pitch.

This is also very predictable. Any hitter who watches film or uses data to prepare for games will know to watch for the slider in the same spot. It also does not help that he throws his curveball in the exact same locations as his fastball.

This is the heat map for his curveball this season. It looks very similar; in fact, it looks almost the exact same as his slider. This makes it very simple for a hitter. Look for the fastball in the zone or an off-speed pitch low and outside, if the batter is right-handed. Mikolas has managed to maintain effectiveness with his curveball as his wOBA against has risen by just .007, from .257 to .264. This is largely due to an elite spin rate of 2590. However, his slider, with much less spin (2216 rpm) has not been so fortunate.

When a hitter is expecting to see a pitch in the exact spot where it lands, it is much easier to distinguish between a strike and a ball. It is also much easier to see a hanging pitch and crush it. Mikolas needs to change his location in order to make himself less predictable.

His slider could be more effective if he mixed locations better in order to distinguish it from his other off-speed offering (curveball). He also needs to tempt the opposing hitter more in order to get more swings and more chases out of the zone. If he can do this he might regain some of the effectiveness that made his slider his best pitch last season, and in turn, remedy some of the problems he is experiencing with allowing home runs and hard contact.