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Is Zack Littell the best starting pitching prospect in the Twins organization?

Although not as well known as fellow pitching prospects Stephen Gonsalves and Fernando Romero, Zack Littell had perhaps the best season of any Twins starting pitching prospect in 2017.

Littell, acquired at the trade deadline in the Jaime Garcia trade with the Yankees, pitched a total of 157 innings between the two teams’ systems, splitting his time between High-A and Double-A. In his age 21 season, Littell had a 2.12 ERA and 22.5% strikeout rate. And if win-loss record is more your flavor, Littell’s 19-1 record is eye-catching.

A self-described command and control pitcher, Littell features a 4-pitch mix that keep hitters off balance, despite a fastball that only sits in the low-90s.

“I realized pretty quickly once I got into pro ball I wasn’t going to be a power guy, I was going to have to rely on command,” he said last season. “If you look at the velos they’re all very average. I try to get as many groundballs as I can, let my 2-seamer and my slider work. I’m looking to get the batter out in three or less pitches, whether it’s a groundball or strikeout.”

Littell isn’t ranked nearly as highly on prospect lists as Gonsalves and Romero. According to, Littell ranks as the No. 16 prospect in the organization, while Gonsalves and Romero rank 3 and 4, and are listed by several publications as top 100 overall prospects.

Nevertheless, traditional numbers from last season suggest Littell was every bit as good as the top two pitching prospects in the organization. Pitching significantly more innings than Gonsalves and Romero at a younger age, Littell’s ERA bested both by more than a run.

Now, it’s admittedly not a perfect comparison, because Littell pitched about 45% of his innings at High-A before moving on to Double-A, where Gonsalves and Romero spent most of their seasons. Nevertheless, Littell’s ERA was better than both even once he got to Double-A, despite being a year younger.

So, should Littell be thought of as a prospect on par with Gonsalves and Romero? Or do his secondary numbers suggest 2017 was an aberration rather than representative of who he really is? To better answer that question, let’s dive into the analytics from each pitcher’s 2017 campaign.

First, the basics. Here’s how Littell, Gonsalves and Romero compared in terms of innings and ERA last season:

Player IP ERA
Littell 157 (85.2 at AA) 2.12 (2.42 at AA)
Gonsalves 110 (87.1 at AA) 3.27 (2.68 at AA)
Romero 125 (all at AA) 3.53 (all at AA)

Littell was clearly the best pitcher of the three in terms of ERA, even when looking only at his stats in Double-A. Unlike Gonsalves and Romero, he also was able to stay healthy all season and pitch more innings.

ERA isn’t a perfect stat, though. It’s possible Littell had an abnormally high percentage of balls in play converted into outs, or that Gonsalves and/or Romero were victimized by poor defense, which would negatively affect their ERAs. FIP (fielder independent pitching) can help us figure out whether that was the case. When a pitcher has a much higher FIP than ERA, it suggests they likely performed above their mean due to an inordinately high number of balls in play being converted into outs.

Here’s a look at each pitcher’s FIP in 2017. I’ve also included strand rate, which is the percentage of base runners left on base. If a pitcher is leaving an unusually high number of runners on base (the major league average is around 72%), that can help explain a discrepancy between their ERA and FIP. Here’s how the three compare:

Player FIP Strand rate
Littell 3.03 (2.89 at AA) 79.5% (74.7% at AA)
Gonsalves 3.22 (2.88 at AA) 76.3% (78.4% at AA)
Romero 2.93 (all at AA) 69.2% (all at AA)

Littell, Gonsalves and Romero all have similar FIPs. Littell’s FIP had the highest discrepancy relative to his ERA, in part because he had a higher strand rate than Romero or Gonsalves. Nevertheless, the numbers suggest that even after controlling for defense and strand rate, they pitched at similarly effective levels last year.

Despite being a pitcher who prides himself on command, Littell gets his fair share of strikeouts, while keeping walks to a minimum. Here’s how the three compared last season on strikeout rate and walk rate.

Player K% BB%
Littell 22.5% (24.3% at AA) 6.5% (7.5% at AA)
Gonsalves 26% (27.3% at AA) 6.8% (6.5% at AA)
Romero 22% (all at AA) 8.3% (all at AA)

In this case, Gonsalves was the superior pitcher, striking out a significantly higher percentage of hitters while walking a lower percentage. Littell, though, had better numbers in both categories than Romero.

Finally, let’s look at hard contact. Specifically, line drive percentage and home run rate. Line drives are bad news for pitchers. A high percentage of balls in play that are classified as line drives suggests a pitcher is giving up a lot of hard contact. Home run rate is the number of home runs they give up per nine innings. I’ve also included ground ball percentage here, because Littell is a pitcher who prides himself on getting a lot of them.

Player LD % GB% HR/9
Littell 17% (18.1% at AA) 52.7% (52% at AA) 0.5 (0.42 at AA)
Gonsalves 20.7 (19.2% at AA) 33.3% (33.5% AA) 0.9 (0.72 at AA)
Romero 22% (all at AA) 52.0% (all at AA) 0.29 (all at AA)

Among the three, Litell gave up the lowest percentage of line drives, induced the highest percentage of ground balls, and was second in home run rate. Gonsalves, a fly ball pitcher,  gave up the most hard contact, both in Double-A and overall. Romero had a similar ground ball rate as Littell and surrendered the fewest home runs, but had the highest line drive rate.

Before we summarize the data, an important note: The numbers presented here are right in line with Littell’s career numbers; there weren’t any significant outliers. At least in terms of his minor league track record, this is pretty much who he is. The same goes for Gonsalves and Romero; their 2017 statistical seasons were more or less in line with their career numbers, though Romero has a relatively limited sample size and a bit more variance.

All right, so what does all of this suggest? We can draw a couple of conclusions:

1) Littell’s 2017 was on par with, and arguably better than, what we saw from the Twins’ two most prized pitching prospects, Gonsalves and Romero. Littell’s traditional and advanced stats show he was just as effective a pitcher, while pitching mostly at the same level. He put up those numbers at a younger age, while enduring a mid-season trade.

2) Because all three had seasons in line with their career averages, we have a large enough sample size to suggest that Littell has been as good as Gonsalves and Romero have been throughout their respective careers. Littell may not have the same level of hype, but to the extent that minor league numbers predict major league success, Twins fans should have similar expectations for all three pitchers as they ascend to the big leagues.


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