The title of the article is an allusion to Schott’s Miscellany, which you should definitely check out if you never have and feel compelled to know that a group of larks is called an exaltation or that a member of the 32nd degree of Freemasonry is known as a Sublime Prince of the Royal Secret.

—Chris Bassitt’s Differential–

Chris Bassitt is the type of player that I tend to miss on in fantasy. He has never been a heralded prospect. Our own Kiley McDaniel did not rank him in the White Sox’s top prospect list in 2014, and he finished just 16th on his new team Oakland’s list prior to this season. In the upper minors, he has eclipsed a strikeout per inning, but his 29.2 innings in the majors in 2014 featured a meager 6.4 strikeouts per nine and unsettling 3.9 walks per nine. Even with a lack of established options behind Sonny Gray that promised a chance at some point in 2015, I overlooked Bassitt in favor of prospects I considered to have higher upsides like Luis Severino, Jon Gray, and Eduardo Rodriguez.

Then, Sunday happened. Bassitt struck out 10 Astros in 6.2 innings. Meanwhile, that performance came on the heels of starts with seven and six strikeouts in his previous two outings, which has raised his strikeout rate to 7.3 per nine and decreased his ERA to 2.48. In two weeks time, Bassitt went from completely off my radar to perhaps the No. 2 starter on a team in a pitcher-friendly park.

I missed my chance to pick up Bassitt in my league—although he is still available in 78 percent of Yahoo! leagues, so check your wires—and I wanted to see if I could figure out what he had that I was missing. I think I found the answer in his repertoire. Bassitt has dramatically increased his reliance on his fastball this season, which could be part of the answer. More intriguing to me, however, was that he had increased his average fastball velocity from 91.8 mph in 2014 to 92.9 mph this season while decreasing his average changeup velocity from 83.1 mph to 82.7 mph. That increase in his differential of 1.5 mph—and it is even bigger per PITCHf/x—struck me as being rather large. As it happens, it is tied for the third largest among primary starters with at least 500 pitches thrown in both 2014 and 2015.

It is a pretty incredible list. Clay Buchholz, Lance Lynn, and Chris Archer might be the three biggest breakout starters in baseball this season. Mike Bolsinger goes mostly unnoticed on the star-laden Dodgers, but he has been a two-win pitcher for the club over 16 starts. And Bassitt is on the leaderboard with them. In recent previous seasons, the leaders have included other breakout starters like Scott Kazmir (1.6 mph) and Phil Hughes (0.9 mph) in 2014 and Jake Arrieta (1.5 mph) in 2013.

There are plenty of clunkers on the leaderboards, as well, and there does not seem to be a definitive overall trend. There are 244 starters who have increased their differential by 0.8 mph or more from one season to the next since 2002, and their combined ERA has been about the same (4.21 and 4.17) before and after the change. Still, the fact that so many of the recent breakout starters have landed on the list makes me consider it as a speculation indicator. I plan to keep my eye on similar starters in the future. For now, I may be stuck lamenting the fact that I discovered the trend a week too late to add Bassitt.