What's FIP got to do with it anyway?

Last month, colleague Ashley Marshall tackled BABIP as a means of re-evaluating the 2013 seasons of some of the game's top prospects. In that same vein, let's look at another important statistic: FIP.

It happens in backyards across the country, and more than ever, around the globe. Two friends, a bat and a ball. One pitcher, one hitter, only a handful of possibilities. The hitter either cranks it over the (sometimes make believe, sometimes neighborly) fence or fails trying. Sure, you can fill in variations of your own, but the sentiment is the same.

Of course, the game of baseball is very different. There are fielders, singles, doubles, triples, groundouts, lineouts, stolen bases, etc. There are more variables in place, and with more variables in place, it becomes tougher to evaluate just how good any one performer is, especially pitchers.

This is the point when you might butt in saying ERA is a pretty good evaluator, and that's mostly true. The end game for pitchers is to allow as few runs as possible, and ERA helps to describe that by giving an average of how many earned runs a pitcher allows per nine innings. It even tries to control for defense by only counting "earned" runs rather than runs that may have scored via an error. But if you've ever watched a game and stared at the scoreboard to see whether that stumble-turned-close-play-at-first is ruled an error or a hit, you know just how fickle an error can be.

So let's strip that away. Heck, let's strip away defense entirely. Let's look at Fielding Independent Pitching (FIP). In other words, let's go back to the backyard.

Background

As outlined by FanGraphs, FIP was first devised by Voros McCracken as a way to look at pitchers without taking into account the amount of hits that get through the defense. It only looks at home runs, strikeouts, walks, hit batsmen -- things the pitcher can control -- and of course, innings pitched. The formula is as follows:

FIP= ((13*HR)+(3*(BB+HBP))-(2*K))/IP + constant (usually 3.2)

Some quick observations on the above. Home runs are obviously weighted much more heavily than the other outcomes because they do the most direct damage. Walks and HBPs carry more weight than strikeouts because they a) are usually fewer in number and b) have more of an impact on the game at hand. The constant, which is explained in greater detail by FanGraphs, is simply a means of getting the number on a similar scale to ERA. It's calculated by taking the average ERA and subtracting the average FIP (obviously sans constant). After crunching the numbers, the average ERA across the 16 domestic Minor Leagues was 3.92 and the average FIP was 0.54, meaning the constant I used here was 3.38 -- a little higher than the 3.2 average constant. (This is how I arrived at the numbers you'll see below, which are slightly different from those at FanGraphs, which use the 3.2 constant.)

The most impressive pitchers in terms of FIP are hurlers who -- surprise! -- get a lot of strikeouts and don't allow many walks, HBPs or home runs. Those should be good pitchers in general. To put the effect of FIP into perspective, rumored Phillies signee A.J. Burnett ranked 18th in the NL in ERA (3.30) last season but checked in much higher at fifth in terms of FIP (2.80). That means the right-hander was hurt, or at least wasn't all that helped, by a Pirates defense that ranked 10th in the NL in UZR/150.

With all that in mind, let's give a FIP-based look at the 40 pitchers included in MLB.com's Top 100 prospect rankings. (Here's a handy table for relevant stats for all of those hurlers.)

Best of the bunch

C.J. Edwards' 2013 season and FIP were a match made in statistical heaven. His incredibly high strikeout rate (155 in 116 1/3 frames) immediately catches the eye, but his ability to keep the ball in the park (one home run allowed all season) is what truly makes him a great candidate in the eyes of FIP (and his ERA was even better). That's part of what we took into account when our staff voted the Cubs right-hander our MiLBYs Starting Pitcher of the Year. 

Edwin Escobar, on the other hand, might be the biggest surprise name in the group above. The Giants southpaw was undoubtedly impressive in 2013 with a great strikeout rate and low walk, HBP and home run rates. He did not, however, rank in the top five in any of those categories among Top 100 prospects. Instead, his across-the-board steadiness vaulted him into the No. 2 spot in FIP. Indeed, it was that production that led to his rise from Giants No. 10 prospect in 2013 to No. 2 in the system and No. 95 overall going into 2014. 

Kyle Crick (Giants) and Rafael Montero (Mets) are mirror images of each other in terms of profile and FIP. The former is a big right-hander who relies on his impressive fastball and slider to rack up the K's while doing the same with walks. The latter's stuff isn't as great and, at 6-feet tall, he's rather diminutive for a pitcher, but he earns marks on the stats page and scouting report for his ability to command the strike zone, highlighted by his zero in the HBP category last season.

Alex Meyer (Twins) has a similar FIP profile to Crick but dropped by allowing two more home runs (three to one) last year.

Worst of the bunch

Trevor Bauer's 2013 struggles have been well documented. FIP just adds another layer to that. He was among the worst in walk (first), home run (second) and HBP rates (0.96) among Top 100 prospects. Put another way, the Tribe right-hander had the second-highest FIP in the International League, trailing only Reds right-hander Daniel Corcino's 5.65. 

FIP doesn't shine the best light on Mike Foltynewicz (Astros) either, although that's predictable given his repertoire. He's got a monster fastball -- MLB.com gives it an elite 80 grade -- but is lacking breaking stuff, which meant the strikeout numbers weren't as good as his fellow prospects. His 1.50 groundout-to-airout ratio in the Minors shows he consistently got his outs on the ground, where he needed his defense to convert them. The infielders at Class A Advanced Lancaster and Double-A Corpus Christi both seemed to do that well, which is why he has a gap between his ERA and FIP. 

In the cases of Max Fried (Padres), Allen Webster (Red Sox) and Jesse Biddle (Phillies), it's important to note that FIPs around 4.00, like ERA, are considered about average. It's when you put them up against fellow Top 100 prospects that their numbers lose some luster. That being said, each had his faults -- Fried (low K, high BB), Webster (high HR/HBP), Biddle (high BB). 

Oddballs and outliers

Now that we've determined who had the best and worst FIPs among this select group of prospects, let's look at who had the biggest differences -- both positively and negatively -- between their FIPs and ERAs. But first, a quick explainer on what causes such a gulf beween the two figures.

We've already established that FIP, by definition, is meant to strip away the defense, so it stands to reason that pitchers who have a much better ERA than FIP are often groundball pitchers who played in front of a very good infield defense or ones who perform better than average with runners in scoring position, since FIP removes the context of the events. 

Orioles right-hander Chris Tillman is a decent example of both qualifiers. Tillman doesn't exactly make his money on the ground -- he owned a 0.97 GB/FB ratio last season -- but he no doubt was helped by a Baltimore left side that featured defensive wizards Manny Machado and J.J. Hardy. He also left 80.5 percent of runners on base, good for sixth in all of baseball. Meanwhile, his 1.44 HR/9 was third-highest among MLB qualifiers, and his 7.81 K/9 wasn't exactly astounding. His ERA: 3.71. His FIP: 4.42. 

As for the other way, pitchers who may play in front of ineffective defenses or may not be as good with runners on will see ERAs much higher than their FIPs. I turn again to the above example of Burnett, who owned a 2.33 GB/FB ratio (third-highest in MLB) in front of a lackluster Pirates infield defensive corps while his 71.8 percent left-on-base rate was 22nd highest among all qualified pitchers.

In sum, you might want to look more favorably upon those whose FIPs are lower than their ERAs -- it might not be their fault -- and turn a more critical eye toward those for whom the opposite is true, given that their low ERA might not be entirely their doing. 

• Who had the biggest drops from ERA to FIP in the Minors? The Royals' Kyle Zimmer (-1.07), the Orioles' Kevin Gausman (-0.84) and the Red Sox's Matt Barnes (-0.62) all saw their ERAs lag behind their FIPs by at least a half-run. Zimmer and Barnes could have seen both numbers drop even lower had they not both put up high home run rates (0.91 HR/9 and 0.87 respectively). For those three, the somewhat high ERAs are likely a bit deceptive, and the true talent level may be found in their FIPs.

• Meanwhile, the Rays' Taylor Guerrieri (1.80), the Rockies' Eddie Butler (1.61) and the Marlins' Andrew Heaney (1.47) can be considered beneficiaries of favorable batted-ball outcomes. Guerrieri, in particular, is an example of a more extreme case like Foltynewicz -- not many strikeouts (6.85 per nine), some control issues (1.34 HB/9) and high groundball rates (3.09 GO/AO). 

• The Mets' Noah Syndergaard (0.01), the Royals' Yordano Ventura (-0.05), the Blue Jays' Marcus Stroman (0.09) and the Astros' Lance McCullers (-0.09) were the four pitchers whose FIP was closest to their ERA, meaning their respective defenses didn't hurt their traditional numbers but didn't exactly help them either. In all, 13 of the 40 pitchers evaluated had FIPs within 0.25 runs of their ERAs in either direction. The average gap between the studied pitchers ERA and FIP was 0.58 runs.