Toolshed: FIP and top prospects

"Yeah, but what about his FIP?"
Fielding Independent Pitching isn't quite on the same level as ERA when it comes to standard baseball jargon, but that is something more and more fans have been asking around the game in recent years. ERA is easy to understand. How many earned runs did the pitcher give up over nine innings on average? FIP is a little less so. How much of an effect did the pitcher have on the game when we take out plays involving the defense? FIP and its context also can tell us different things about a pitcher's performance and should be a tool most fans and evaluators at least check up on.

For the uninitiated, FIP is measured by what a pitcher typically has control over -- strikeouts, walks, hit batsmen and home runs. In other words, it takes out the defense completely, something ERA can't do given its formula. The calculation for FIP is as follows -- ((13HR)+(3(BB+HBP))-(2*K))/IP + constant. (FanGraphs goes deeper into FIP's equation here.) In this column, we'll consider the constant, used to put FIP on a similar scale to ERA, to be 3.55 as calculated by using 2019 data from all 16 domestic Minor Leagues.
Consider all of that together, and these were the best Top-100 prospects from the 2019 season, according to FIP.

Lowest FIPs by Pitchers among MLB.com's Top 100 Prospects (min. 75 IP)

Put another feather in the cap of Balazovic during his breakout season.
Ranked as the No. 19 prospect in the Twins system to start the 2019 season, the 21-year-old right-hander jumped to No. 4 with his strong campaign at Class A Cedar Rapids and Class A Advanced Fort Myers. The 6-foot-5 hurler is capable of throwing in the mid-90s and earns above-average grades on his slider. Back in July, he also credited the development of his changeup as a solid third option for his impressive jump this summer.
That three-pitch mix helped Balazovic out the most in the strikeout department with the Ontario native fanning 33.9 percent of the batters he faced between the Midwest and Florida State Leagues. That placed 13th among all Minor League pitchers with at least 75 innings this season and fifth-best among Top-100 prospects who fit the same standard behind Tarik Skubal (36.5), MacKenzie Gore (35.7), Grayson Rodriguez (34.2) and Deivi Garcia (34.0). Balazovic also earned points for throwing the ball consistently in the zone with just a 6.6 percent walk rate between both spots. That's not quite elite -- it placed 207th among the 746 Minor Leaguers with at least 75 innings -- but it is solid. What's especially important, though, is the way Balazovic married high strikeouts with his walks. His average of 5.2 strikeouts per walk was the best among qualified Top-100 prospects, just above Logan Gilbert (5.0) and Sixto Sanchez (4.9).
Perhaps Balazovic's biggest advantage was in the home run department. The Twins hurler played in two relatively pitcher-friendly leagues when it came to dingers. In the Midwest and Florida State Leagues, 1.6 percent of plate appearances ended with long balls -- the two lowest home-run rates among full-season leagues in 2019. Balazovic beat that low average with his 1.0 percent mark, but it didn't hurt that he called both home, especially when 3.6 percent of Triple-A plate appearances ended with balls over the wall. That could come back to bite him at upper levels with Balazovic surrendering fly balls on 45.1 percent of his batted pitches in 2019, compared to 42.3 percent grounders and 12.7 percent line drives. But for now, it's part of the equation that led to pure dominance in 2019.
Elsewhere on the above chart, Skubal's K-heavy approach moved him into the second slot. The Tigers left-hander only got better in that department as the season wore on and fanned double-digit batters in six of his final nine appearances for Double-A Erie. Only Kris Bubic (185) and Joe Ryan (183) had more punchouts than Skubal's 179 in the Minors this season and both pitched more innings. Like Balazovic, Gray earned the most points on his ability to keep the ball in the yard, giving up three homers in 130 innings -- all at Class A Advanced Rancho Cucamonga despite the fact he played at two other levels). But the Dodgers righty still gave up many fly balls (45.5 percent), so it'll be interesting to see if his four-pitch mix can get as weak contact against upper-level bats over longer stretches in 2020. Gilbert got off to a promising start in his first full season with the Mariners, climbing three levels and striking out at least 28.7 percent of the batters he faced. More on Gore below.

Biggest drops from ERA to FIP among MLB.com's Top 100 Prospects (min. 75 IP*)

The above lists the pitchers for whom FIP is a much kinder stat than ERA. That is to say, these are the prospects who may have performed better had the game been limited to simple homers, strikeouts and walks.
We included an asterisk here because Whitley was so far ahead in this category that he needed inclusion, even if he did miss the innings mark due to shoulder issues. It's no secret the Astros' top prospect endured a difficult 2019, especially at Triple-A Round Rock, where he posted a 12.21 ERA with nine home runs allowed and 15 walks in 24 1/3 frames before his move to the injured list in late May. In essence, Whitley was hit hard everywhere. But FIP says he wasn't hit as hard as ERA alone tells you. It's true a 5.48 FIP isn't great in the same way that a 5.48 ERA wouldn't be great, but it's a heck of a lot more palatable than a 7.99 ERA. The 22-year-old right-hander still earns impressive marks for his four-pitch mix when he can command it and that resulted in a 30.9 percent K rate -- about the same as flamethrower Nate Pearson (30.7). Getting everything else figured out will be the goal for 2020 after his turn in the Arizona Fall League, but for now, Houston's only Top-100 prospect has more of a cause for optimism than based on other factors alone.
Well below Whitley is Garcia, who trended in the other direction from his Houston counterpart in 2019. The Yankees right-hander was downright elite at getting whiffs, especially at Class A Advanced and Double-A, where he fanned 120 in 71 1/3 frames while producing a solid-but-not-spectacular 3.66 ERA. The 5-foot-9 hurler's control can waver, but he was hurt by a below-average 69.9 percent left-on-base rate and a .348 BABIP -- both of which can be related a bit more to team defense. Knowledgable New York fans knew to be excited by Garcia's plus fastball and plus-plus curve, but for anyone scared by his 4.28 ERA, FIP should provide some relief.
May and Hall posted FIPs relatively close to their ERAs -- so close that the more advanced stat doesn't tell us anything new.

Biggest drops from FIP to ERA among MLB.com's Top 100 Prospects (min. 75 IP)

On the flipside, larger FIPs than ERAs can take a little of the shine off otherwise really impressive seasons. 
Cabrera climbed into the Top 100 for the first time on the strength of a plus-plus fastball that can touch the high-90s and an above-average slider. Those helped him average above one strikeout per inning between Class A Advanced Jupiter and Double-A Jacksonville, but at the latter, he may have been a little lucky when it came to contact. The 21-year-old right-hander gave up just a .242 BABIP in eight Southern League starts and stranded 89.9 percent of the batters who reached base. (Even 80 percent is considered high.) That may have kept his ERA down to 2.56, but his peripherals (notably the six homers allowed in 38 2/3 innings) resulted in a much higher 4.58 FIP at the second-highest level. It's a smallish sample, so there's plenty of cause for high hopes with Cabrera entering 2020. Just temper those slightly.

When it comes to Gore, it's tough to look better than his 1.69 ERA, and as his fifth spot in the overall FIP table above shows, his number in that category looks pretty good too. But whereas Gore ranked fifth in ERA among Minor Leaguers with at least 75 innings in 2019, he placed 41st in FIP. The culprits -- an astoundingly high 88.1 percent left-on-base rate and an astoundingly low .239 BABIP. The Padres' top prospect has two plus pitches in his fastball and curve and two above-average ones in his slider and change to get plenty of swings and misses wherever he goes, and despite a high leg kick, he typically thrives at finding the zone with regularity. But if (gasp) his ERA isn't in the 1.00's next season, it's not a sign of his ability going south. It's just his ERA catching up to his otherwise sterling FIP.