Over the past year, Lewis Thorpe has exploded on the scene. An unknown commodity heading into the GCL last season, he was so dominant as a 17 year old that he has appeared on various preseason Twins’ top 10 prospect lists. He has made even more news this year, skipping the Appalachian league and going straight to A ball from extended spring training. However, the Midwest league has not been kind to Thorpe, who has posted a 5.40 ERA with a 31:15 k:bb ratio in 35 innings over 8 GS. Despite these struggles, Thorpe is showing sign of improvement.

Moving in the Right Direction

Thorpe improvement is easily noticed when looking at his monthly splits:

June: 4 GS 18 IP 6.50 ERA 1.67 WHIP 7:10 k:bb

July: 4 GS 17 IP 4.24 ERA 1.18 WHIP 24:5 k:bb

Although Thorpe's ERA has remained high, it is significantly lower than in the month of June. Furthermore, his WHIP has plummeted to a very respectable level. Most importantly, his k:bb has gone from and atrocious .7 to a stellar 4.8. In fact, his K rate 33.3% is higher than that of the league’s leader this season (29%) and his K/BB would be good for second in the league¹.

A deeper way to examine Thorpe's improvement is to look at rolling 4 start stretches, which are rarely used when discussing baseball, but are commonly used in finance. The general idea is that this will allow us to get a more detailed look at how Thorpe has improved start to start (how much better was he in start 5 vs. start 1) while at the same time maintaining a larger sample size. In short, this will allow us to see how consistent--or inconsistent—Thorpe’s improvement has been.

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Although his ERA has moved around a bit, his WHIP, K%, BB%-- and therefore K:BB ratio-- have decreased each period. Furthermore, his opponent's OPS has decreased each time with one exception. This kind of consistent improvement makes me confident that Thorpe is getting comfortable in A-ball and that his strong performance should continue the rest of the season. Furthermore, it proves that his strong month of July isn’t merely the result of one incredible performance.

Going Forward

I will be looking forward to Thorpe’s start tonight, to see if he can continue his run of success. Even if Thorpe is excellent for the rest of the season, I would argue that he should begin 2015 in Cedar Rapids. The reason? His youth. At 4 full years younger than the average pitcher in the league and 11 months younger than Kohl Stewart—the youngest pitcher to be qualified for the ERA title—Thorpe would probably be the youngest pitcher on an opening day roster in the Midwest league next year. In other words, there is no need to push him. However, Thorpe's youth is so extreme that its impact stretches far beyond this usual argument. Thorpe appears to have been on a very strict pitch count: according to the Cedar Rapids Gazette, he is being limited to 75 pitches a night. Furthermore, if Berrios’s age 19 season in Cedar Rapids is any indication, Thorpe probably won't pitch more than 120 innings next year². Not only would it be nice for Thorpe to learn how to go deeper in games at an earlier level, but if he were to begin next year and ft. Myers and move up one level per year, there's a good chance he would reach AAA never having thrown more than 150 innings in a season, nor consistently reached 100 pitches/GS. While that may not be a bad thing, it certainly isn't ideal for a pitcher just one step away from the MLB. For now though, let’s hope that Thorpe continues to improve here in 2014, in which case he could appear quite high on Top 100 lists, and would provide the Twins with another potential front of the rotation starter for years to come.

1. I would have liked to have compared this to the league leaders for July, but I couldn’t find that data.

2. Berrios, who did seem to wear out as the year went along, pitched just 103.2 innings