When I’m evaluating pitching prospect statistics, I look first at three numbers: walk rate, strikeout rate, and groundball rate. And when I am weighting those numbers for ranking purposes, I typically put more slightly weight on groundball rate. Mechanical changes and work on new pitches can really throw off strikeout and walk rates, but, in general anyway, groundball rate tends to be more resilient. Besides, grounders appear to correlate well with all sorts of things that are good for pitching prospects: good movement, good location, good breaking stuff, and the ability to avoid consistent hard contact. Moreover, when it comes to batted ball designations, keeping accurate track of ground balls might be a little easier than some other batted ball types and classifications.
Lately, though, I’ve been increasingly looking to line drive rate, particularly when it comes to pitching prospects, and particularly in relationship to groundball rate. The thinking goes something like this:
The best batted ball outcome for a pitcher, on average, is a ground ball. Therefore it is a good thing if a pitcher gets a lot of ground balls.
The worst batted ball outcome for a pitcher, on average, in a line drive. Therefore it is a good thing if a pitchers does not give up very many line drives.
Per FanGraphs (these are 2014 Major League numbers), hitter wOBA on a grounder is .220. On a flyball it is .335. And on a line drive it is all the way up to .684. When you consider that wOBA is scaled to feel a lot like batting average, you get a sense just how dramatic those numbers are.
On average, per the same source, a line drive occured in 20.3% of at bats last season, a grounder in 44.2%, and a fly ball in 35.5%. Those numbers don’t change very much year over year.
Any pitcher, then, who can consistently post a groundball rate well above 44.2% would be considered a good groundball pitcher (I usually look for 50% as a good rule of thumb number when studying prospect stats). And any pitcher who can consistently a line drive rate well under 20% would be a good not-line-drive pitcher.
While it remains to be seen just how useful line drive rate will be in projecting prospects both hitting and pitching, pulling line drive rate into the equation has done something that I did not think would ever be possible. It has explained Brad Markey.
Brad Markey is an ostensibly fringe pitching prospect in the Cubs farm system who for a couple years was notorious for putting together really good seasons on the basis of some not-good peripheral numbers. I first noticed him in 2015 when he happened to be on the mound for a Myrtle Beach game I went to watch, and after he seemed to struggle early, I looked up in the sixth and suddenly realized he’d been cruising for innings and was barely giving up any hard contact at all.
In 2016 in 130 innings for Tennessee, Markey somehow managed an ERA of just 3.17 despite a crazy low strikeout rate (4.48 K/9), a mediocre walk rate (3.10 BB/9), and a groundball rate that was only par (44.4%). Every time I thought I was starting to understand pitching prospects I’d take a look at Markey and decide to do something easier – like juggle dumpsters while doing headstands on a unicycle balanced atop a launching Falcon 9. You know, possible things.
But no more. In 2016 Markey posted a line drive rate of 15.4%, very far under our benchmark of 20%. Markey, the numbers finally demonstrated, was finding success with a lot of weak contact in the air. And he has managed to do so at every stop since his first full season as a professional.
Finding a model improvement that explains minor league events I previously couldn’t is a fairly big deal, and it is why my models are constantly in flux. Since I can’t exactly watch all 200+ prospects that I cover play regularly, I rely very heavily on the stats to tell me things my eyes are missing. That means I need to get my eyes and my stats into as much agreement as possible. Line drive rate looks like it may help with that.
Taking a look around the minors, it’s not hard to see that the Cubs have been targeting guys who avoid hard contact (line drives) for some time, even if they didn’t otherwise have the kinds of strikeout and walk rates you’d want to see.
Sitting among the league leaders in this category in the Pacific Coast League last season (min 60 innings) was Seth Frankoff. He signed with the Cubs as a minor league free agent, had a decent season, and turned it into a contract to play in South Korea. Also near the top of the list was Luke Farrell, claimed by the Cubs from the Reds in October.
In the Double A Southern League, the league leader in this category was Daury Torrez at just 12.3%. James Pugliese, Preston Morrison, Zach Hedges, and Jen-Ho Tseng all joined him near the top of the leaderboard. Setting the minimum at 40 innings, five of the top sixteen were Cubs’ prospects.
Dropping to Myrtle Beach (still min of 40 innings), once again it is a Cub atop the leaderboard. Oscar De La Cruz is in first with an anemic 12%. Dakota Mekkes, Pedro Araujo, and Michael Rucker all sneak into the Top 30, joined by an absolute army of Astros prospects (maybe the Cubs aren’t the only stat-driven front offices thinking along these lines…).
In the Midwest League, the Twins dominate the leaderboard, but Bryan Hudson (12.9%), Duncan Robinson, Erling Moreno, Tyson Miller, Wyatt Short, and Manuel Rondon all come in at 15% or lower for the Cubs.
The Nortwest League did not show as well for the Cubs (although Bailey Clark kept them on the leaderboard), but in Arizona we see Faustino Carerra (13.5%) coming in at number two. Brailyn Marquez and Alfredo Colorado also fare pretty well.
Unfortunately, there is a significant hurdle to leaning on batted ball rates in the minors too heavily as outside evaluators. There is no StatCast in the minors. We have no really accurate, really consistent source for numbers like launch angle and exit velocity that can allow us to objectively tell the difference between a line drive and a fly ball. We are at the mercy of the scorekeeper and whoever is coding the game for MiLB.com, and that means we are at the mercy of inconsistent data. One official’s line drive is a fly ball to the next one over.
Ground balls, I like to think, are more objective, but I admit I’m probably kidding myself, at least to some degree. Batted ball rates are going to be fuzzy in the minors for now.
But that doesn’t mean they aren’t useful. I’m still checking to see how well these numbers will hold up as predictive tools, but at the very least they should have value as descriptive ones. I’m pretty confident the 2018 edition of the Top 40 will pull in line drive rates for pitchers to some degree (and maybe for hitters, experiments are ongoing in that department), and then we’ll see from there. And don’t be surprised to see it appear from time to time in the Minor League Daily as well.