Mike Foltynewicz starts this evening for the Braves, and he is closing in on the end of his third year on the club. He’s also now 25 years old, so we ask: is he becoming more effective? Let’s look at the Game Log data from baseball-reference.com. We’ll exclude games he appeared as a reliever (one game this season, three in 2015), which gives us 57 starts for the Braves. What kind of trend lines do we see?
Here we have a plot of every start Folty has had for the Braves. The blue line is the linear trend line, clearly going down.
Here we see the three season as three separate box plots. Each shows the median earned runs, lowest, highest, and the 25th and 75th percentile. So, 50% of his starts were inside the box. Not only are his earned runs per game decreasing, they are less widely distributed (excepting the two high outliers from this season noted in the chart).
Interestingly, he doesn’t seem to have a strong correlation between his strike% (the number of strikes as a percentage of pitches) and either earned runs or Game Score (the Bill James numerical measure of the effectiveness of a start). It would appear being “effectively wild” is a big part of his game. He has already totaled his WAR from last year, and we’re at the beginning of August, so it seems the answer to our question is yes, Foltynewicz seems to be trending in the right direction. Of course, this kind of statement can be a kiss of death, coming right before he gives up 8 runs in an inning, but that’s why you play the games.