Why Fly-Ball Pitchers May Be Better Bets Than Ground-Ball Pitchers

By Eriq Gardner //

One of the fundamentals in evaluating starting pitching is to focus on three key areas where pitchers hold a measure of control over their statistical production:
  1. The ability to retire batters via strikeouts
  2. The ability to limit base-runners by avoiding the issuance of walks
  3. The ability to limit home runs by keeping the ball on the ground

Pitchers who do a good job at these three things are commonly assumed to be very skilled. Pitchers who do these things well but don’t have a superb ERA to match are seen as unlucky.

Makes sense. However, we’re not quite certain that ground-ball pitchers are better fantasy baseball assets than fly-ball pitchers. Perhaps slightly more valuable, yes, but not as profitable. Confused? Read on…
We examined statistics from starting pitchers between 2006 and 2010 to get an idea what kind of production we could expect from starters who were elite at keeping the ball on the ground versus starters who were terrible at keeping the ball on the ground. We put the pitchers into four quartiles:
  • Pitchers with elite ground-ball skills (above 47 GB%) including stars like Felix Hernandez and Chris Carpenter and lesser ones like Paul Maholm and Aaron Cook.
  • Pitchers with above-average ground-ball skills (about 44.5%-47%) including stars like Tim Lincecum and CC Sabathia and lesser ones like Joe Saunders and Jeff Suppan.
  • Pitchers with below-average ground-ball skills (about 40.5%-44.5%) including stars like Jake Peavy and Cole Hamels and lesser ones like Kevin Millwood and Kyle Lohse
  • Pitchers with terrible ground-ball skills (below 40.5%) including stars like Jered Weaver and Matt Cain and lesser ones like Jarrod Washburn and Oliver Perez.

Now, let’s look at each of the categories.

First up, here’s a look at ERA for each of these groups. You’ll notice that the ground-ball “elite” have a superior advantage over the rest of the field. It’s easy to understand why. Pitchers who don’t give up a lot of fly balls save themselves from the trouble of allowing many home runs, which tends to very unhealthy to a pitcher’s ERA. 
However, also notice that pitchers with “terrible” ground-ball rates perform better in ERA than pitchers with “below-average” and nearly as well as “above-average” ground-ball rates.
It should be no surprise that the category of WINS tracks similarly. After all, there’s a pretty strong correlation to preventing runs and getting wins. Pitchers with “elite” ground-ball skills do best in wins, but perhaps surprisingly, pitchers with “terrible” ground-ball skills don’t do as badly as pitchers in the 25%-75% range.
So far, we’ve shown that elite ground-ball pitchers have the edge. Let’s now turn our attention to WHIP. Surprise! Pitchers with “terrible” ground-ball rates are the best of the bunch:
Maybe non-HR fly balls are easy to field than ground balls and that’s why pitchers with terrible ground-ball rates have good WHIPs. 
Here’s another theory: These pitchers tend to pound the middle of the strike zone instead of nibbling near the bottom of the strike zone. As supporting evidence, we now present a look at how each of these four groups of pitchers perform in the STRIKEOUT category. As you’ll see below, pitchers with terrible ground ball rates typically get the most strikeouts:
Obviously, ground-ball rate doesn’t always go hand-in-hand with strikeout rate. There are definitely pitchers like Ubaldo Jimenez who do a great job of keeping the ball on the ground and getting strikeouts. But the norm tends to be that fly ball pitchers do better at inducing whiffs.
Add it up and we have two categories (ERA, W) favoring pitchers with elite ground-ball rates and two categories (WHIP, K) favoring pitchers with terrible ground-ball rates. Based on the fact that wins tend to be most scarce, the edge in overall fantasy value goes to pitchers with elite ground ball rates. But do fantasy folks overestimate that edge?
Many competitors tend to focus on the sexy stats of wins, strikeouts, and ERA and give short shrift to a category like WHIP. The pitchers commanding top prices in fantasy drafts do very well in those first three categories.
How about some fly ball pitchers? The top pitchers include Cliff Lee and Jered Weaver. As for the potentially longer list of draft day bargains, think Ted Lilly, Ricky Nolasco, Scott Baker, Javier Vazquez, and Aaron Harang. Each of these players are fly ball pitchers who project to have great WHIPs and strong strikeout rates. 
At very least, there’s a floor to their prospective value that makes them good bets to at least earn back their draft investment. 
The upside for more is also there. As demonstrated above, pitchers with terrible ground-ball rates don’t do as badly in ERA and wins as one might assume. Furthermore, each of these pitchers play home games in pitcher’s parks, which may dampen the number of home runs they give up and might, very possibly, make them just as valuable as elite pitchers going very early in drafts.


I think that there might be a bit of a selection bias happening here with your quartile splits, due to poor categorization on the part of baseball’s statisticians.

Clearly, as you note flyballs are worse than groundballs, hence the oddity of your graphs.

I think the problem is that a lot of popups are currently defined as flyballs. Obviously, as a category, popups are up there with groundballs in getting outs, and not like other flyballs, which can become homeruns. I believe a large majority of the pitchers who populate that last category are good at gaining popups.

Now, it is not like popups are not being accounted for, and they are as infield flies, but for some reason baseball has decided that, well, it is more like a flyball than a groundball, so we’ll put it in that category. And, of course, the shallow popups that barely reach the outfield are labeled flyballs too, I bet.

Why they don’t just have a third category, covering all popups, I’m not sure, maybe because way back when, when they were not able to separate the two, and just had flyball vs. groundball, all the stats were created related to the two, and nobody wants to deal with three, where the third are infield flies. Who knows, they just don’t.

Anyway, it would be my supposition that, as our intuition and logic tells us, the flyball pitchers do pitch themselves out of baseball, leaving mostly the popup masters in that last category of low groundballers.

I think with the latest video analysis tools that the MLB is installing (I think AT&T is the first to get them), where they can get a variety of statistics related to how the ball is put into play, there will be some point where they will be able to define popups as balls hit at a certain range of angle upward, with a certain range of power (velocity of ball hit), and analysis such as this post will find different results.

I’ll take a Fly Ball pitcher in a pitcher’s park with a good OF defense over a Ground Baller. The Fly Balls lower the BABIP (a good OF helps that too), but we need the HR/FB% to be below average (hence the pitcher’s park).

A lot of variables involved, but if you cherry pick you’ll find many useful Fly Ballers out there.

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