Breakout Breakdown: Mike Foltynewicz

One reason the Atlanta Braves surprised the baseball world and won the National League East was the strength of the team’s starting pitching. Sean Newcomb turned in a 2 WAR/3.90 ERA season; Anibal Sanchez reinvented himself at age-34; and several youngsters (Michael Soroka, Touki Toussaint) were effective in limited action. But without Mike Foltynewicz’ stellar season, the Braves may not have turned into NL East champs ahead of schedule in 2018.

This year, the 27-year-old Foltynewicz posted a 2.85 ERA (3.37 FIP) and a career best 27.2 percent strikeout rate over 183 innings pitched.

Around midseason, Al Melchior and Rian Watt took an excellent look at how and why Foltynewicz was enjoying a breakout. Watt noticed how Foltynewicz was employing a new pitch mix – throwing his fastball and slider, his two best pitches, more often. He also appeared to be executing them more consistently and pitching with a greater separation in fastball and slider velocity.

A few weeks later, Al wrote about how Foltynewicz had been able to generate a career-best strikeout rate without seeing an improvement in swinging strikes.

Thanks to the great work of these talented writers, we already have a good idea of how and why Foltynewicz was breaking out. The first part of our job is already done. The question becomes: did he continue with these adjustments in the second half? And can they carry over into 2019.

Watt pointed out how Foltynewicz was using his four-seam fastball and slider 68.9 percent of the time compared to 54.9 percent of the time 2017. The increased usage came at the expense of his sinker – which he threw 15.8 percent of the time in 2018 compared to 27 percent of the time in 2017.

As the season wore on, Folty continued to lean heavily on his fastball/slider combo, using the pitches 65.1 percent of the time in the second half – a slightly lower rate than the 68.9 percent usage at the time of Watt’s writing (June 4). While Foltynewicz was able to sustain the increased fastball velocity in the second half (96.2 mph) his slider velocity ticked back up to an average of 87.6 mph, losing some of the separation that Watt noticed he benefited from earlier on in the season.

Foltynewicz also saw his swinging strike rate remain fairly consistent – posting a 10 percent rate in the second half compared to 10.6 before the break. Al’s analysis of the data reveals that strikeout gains without a significant increase in swinging strike rate aren’t likely to be sustainable, and that a league average (10.2 percent for starters) swinging strike rate may not be enough to sustain a K rate in the high 20 percent range. True to Al’s analysis, Foltynewicz’ second half strikeout rate dropped to 24.9 percent from 28.9 in the first half.

While Foltynewicz’ swinging strike rate hovers around league average, his increased slider usage has enabled him to throw his best pitch (in terms of swing-and-miss and results) more frequently in put away situations. According to Baseball Savant, Folty’s slider produced the ninth best xwOBA (.197) among starting pitchers (minimum 200 results). In 2017, Foltynewicz threw his slider 29 percent of the time when he was ahead in the count as compared to 35 percent of the time in 2018.

If he is able to generate a few more Ks with his increased slider usage, sustaining a strikeout rate north of 25 percent is still likely unrealistic. Zack Greinke, a pitcher Al notes profiles similar to Foltynewicz in terms of swinging strike rate,  benefits from elite control and a walk rate far lower than Foltynewicz’. Greinke, who also relies on called strikes, has only posted two seasons since 2013 with a strikeout rate higher than 24 percent.

Even Foltynewicz’ 24.9 percent post-all-star break strikeout rate would be a full-season career high and a significant improvement over the 20.7 percent strikeout rate he posted in 2017.

If he continues to throw his slider and fastball more frequently, as he did in the second half of the season, we are still looking at an improved pitcher. Foltynewicz himself acknowledged that he was indeed trying increase his slider usage – a positive indication that some of the changes he has made will stick in 2019.

Combine a potential modest uptick in his K rate with a mid-3’s ERA that reflects his FIP and Foltynewicz can likely beat his Steamer projection of 4.00 ERA and his pre-2018  strikeout numbers. This should allow him to sustain some of the gains he’s made in 2018. But until he is able to generate more swings and misses, it likely won’t be all of them.