Were all Cardinals fans wrong about Miles Mikolas? Not so fast

On the surface, Miles Mikolas is having a very good season. The veteran right-hander has a 4-2 record with a 3.51 ERA and a 3.68 FIP through 10 starts. If you remove Mikolas's blow-up start against the Boston Red Sox, where he allowed eight runs in just 2.2 innings, Mikolas would have a 2.23 ERA.

He's been a steadying force for the Cardinals' rotation since mid-April, and the team has won the game in his last five starts.

Are Miles Mikolas's stats for real, or are there underlying concerns?

Let's start with expected stats. Mikolas's expected ERA is 4.39, and his expected FIP is 5.00. These expected stats indicate a high probability of regression in the near future.

While Miles Mikolas has never been known as a strikeout pitcher, he has been able to limit walks throughout his career. Mikolas's career walk rate of 4.7% is exceptional. However, he's taken a step back this year from his 3.5% walk rate in 2024. Mikolas is walking 7.5% of the batters he faces. That's still an above-average walk rate, but it is significantly worse than last year. Mikolas is walking more batters and striking out fewer still. He's struck out just 14.6% of batters he's faced, a career-worst figure outside of his 2013 season.

Mikolas's 14.6% strikeout rate places him in the sixth percentile of baseball.

Across the board, Mikolas's underlying metrics are down from last year. His average fastball velocity of 91.7 MPH is down from 92.8 MPH last year. His first percentile whiff rate of 16.4% last year is down even further to 14.8% this year. His groundball rate is down from 42% last year to 38.4% this year.

Where are baseballs being hit off Mikolas, then? Well, his fly-ball rate is up to 45.4% from 36.5% last year. His pull fly-ball rate of 25.6% is nearly the highest in the league. Pulled fly balls and pulled line drives are some of the most dangerous hits.

Last year, Mikolas was one of the worst pitchers when it came to throwing meatballs. A meatball is a pitch thrown in the heart of the plate. Essentially, it's a pitch that hitters should crush more often than not. Mikolas threw meatballs 9.1% of the time in 2024, the third-highest rate in baseball last year. He's only gotten worse at throwing pitches in the heart of the plate this year, with a 9.6% meatball rate. This is the seventh-highest rate in the league.

What is Miles Mikolas doing this year to see more success? For starters, his curveball has been much more effective this year. Opposing batters have a .127 wOBA against it. It's also generating whiffs a quarter of the time, and the average exit velocity against it is just 85.9 MPH.

Mikolas is seeing softer contact across the board this year with a 21.3% soft-hit rate. While softer hits are nice for a pitcher, hitters are bound to catch up with his below-average velocity sooner rather than later. It's also entirely possible that the fly balls he's seeing this year continue to find the Cardinals' outfielders. After all, Cardinal outfielders do rank fourth in Major League Baseball in Outs Above Average as a group this year.

Miles Mikolas's stats on the surface are strong. He has a solid ERA for a bottom-of-the-rotation starter with a near-equal FIP. However, his underlying metrics show that he's due for some negative regression in the near future.