Analyzing Fly Ball Metrics: 2020 Negative Regression Candidates

February 6, 2020

Riley Mrack evaluates fly ball metrics from last season to pick out some starting pitchers that could be negative regression candidates for the 2020 fantasy baseball season.

Last week, I uncovered a few pitching casualties from the record-setting 2019 season, which saw an unprecedented amount of home runs hit and a "juiced" ball theory come into light. While the use of the defensive shift has caused more players to change their swing into a fly ball-oriented approach, this monumental increase in dingers was still outlandish. My personal opinion is that the baseball itself did play a factor in the home run surge, but not every pitcher fell victim to the inflated results.

We don't know if the baseball will remain the same for 2020 or if MLB will re-seam the balls to give it more drag. I anticipate the league using a different makeup for the ball in 2020, but that doesn't necessarily mean all hurlers will improve their home run metrics. Today we'll graze over some pitchers who survived the 2019 home run epidemic but are destined for negative regression for the upcoming 2020 season.

Baseball always has a way of evening itself out and metrics such as HR/9 and HR/FB tend to find a mean for every individual over a large-enough sample size. Statcast measures such as fly-ball rate (FB%), Barrel%, Exit Velocity (EV), and pull rate (Pull%) are crucial when deciphering where a pitcher's home run outcome "should" be. A statistical breakdown in these measures can help us determine who had a fortunate season in 2019 and whose home run susceptibility might increase moving forward.

Mike Clevinger (SP, CLE) 23.2 ADP

A back strain in April limited Mike Clevinger to 126.0 innings pitched last season, and perhaps he didn't get enough of a sample size to regulate his home run data. The right-hander lowered his 0.95 HR/9 and 10.2% HR/FB down to 0.71 and 9.7%, respectively, despite serving up more quality of contact, as indicated by the chart below.

Clevinger's batted ball metrics didn't significantly diminish from 2018, and his EV remained nearly identical with a minor improvement. His pull rate stands out as the most prominent downfall, especially since this rate on his fly balls increased by almost 10% from 2018 to 26.2% in 2019. His average EV on his flies and line drives also rose (91.7 MPH to 92.3 MPH), and he wasn't surrendering wall-scrappers either with a 401' average HR distance (385' in '18).

The long ball has never burdened Clevinger substantially throughout his minor league years, or during his 500 innings of major league action. His homers should level out if the law of averages has it's way, even if his batted ball metrics improve, but I don't expect a monumental increase in big flies next season. I have Clevinger ranked similarly to my fellow RotoBaller rankers as our SP7, but I did have the lowest overall ranking with this baked-in slight regression anticipated.

Charlie Morton (SP, TB) 61.1 ADP

When Charlie Morton resurrected his injury-plagued career with the Astros in 2017, he posted a 0.92 HR/9 and 13.6% HR/FB combined over his two years with the club. He always could limit the long ball dating back to his days with the Pirates, but his change in repertoire helped him become an entirely different pitcher since 2017.

An increase in velocity and usage of his fastball was a major contributing factor to his success as he maintained his groundball-heavy attack with his sinker. As a member of the Tampa Bay Rays for the 2019 season, Morton posted the league's best HR/9 (0.69) while placing in the top-five in HR/FB (10.4%) thanks to some sterling Statcast metrics.

All of Morton's 2019 metrics were below the league average and undoubtedly worthy of a top-tier finish in home runs allowed last season. Still, it's a little unsettling that his batted ball metrics didn't improve considerably in all areas since his home run numbers declined, meaning he had some luck go his way last season. A look into the data on the right-hander's fastball and sinker shows us a Jekyll/Hyde performance.

Morton achieved his lowest fly-ball rate on his sinker last season (4.9%), which was the first time he went below 10% since 2013. He's posted numbers in the low-teens annually, so this number stands out like a sore thumb. Morton's four-seamer, naturally, saw inverse results with his 34.2% FB% sitting as his highest mark since 2012 and a far cry from his 24.5% career figure with the Astros.

The 36-year-old has lowered his sinker usage in each of his past three campaigns, and if his fly ball numbers on this pitch regress to his lifetime levels, he's in danger of losing his elite groundball ability. Of course, Morton's fastball could also normalize back to the mean, but his 1.4 MPH drop in velocity and gradual increase in fly-ball rate throughout the 2019 campaign are trending in the wrong direction. I'm more bearish on Morton than our other rankers; however, I don't expect his home numbers to fall off a cliff, but I foresee his figures returning closer to his time with the Astros.

Sonny Gray (SP, CIN) 103.1 ADP

Sonny Gray had a resurgent year with the Reds a season ago, establishing his best HR/9 and HR/FB numbers since the 2015 campaign with respective marks of 0.87 and 13.0%. He proved to be one of the better pitchers at keeping the ball on the ground (52.6% GB%), but his batted ball metrics didn't show enough to support his ability to keep the ball from reaching the bleachers.

Statcast didn't start recording these measures until the beginning of the 2015 season, so these numbers are weighted heavily from his most home run susceptible years of 2016-2018 (1.12 HR/9). Despite Gray's success last season, it's perplexing that he improved in the HR column since his Barrel% and FB% from 2019 were both his worst marks to date.

Couple these stats with a home ballpark that is only a season removed from topping the list in HR Park Factor, Gray appears primed for negative regression in 2020 no matter what baseball the league uses. I like the two-time All-Star slightly more than my fellow rankers since he keeps the ball on the ground well above the league average, but admittingly Great American Ballpark makes me a bit skittish.

Mike Soroka (SP, ATL) 103.8 ADP

Mike Soroka impressed in his first full big-league season, holding opponents to an 11.1% HR/FB while finishing second in the majors in HR/9 (0.72). Like Gray, a large chunk of his success in this area had to with owning the second-lowest fly-ball rate in the league (15.3%), but as the season progressed, hitter's began to loft the ball more often.

Not only did opposing batters put the ball in the air much more often in the second half, but they pulled these flies at a higher clip from 22.2% pre-All-Star break to 26.4% post-break. Soroka's groundball-rate also plummeted from 59.0% to 46.3% in the second half as he threw his sinker less often in consecutive months since May. Still, this delivery saw its GB% drop from 75.8% to 56.8% from half to half as he allowed the most dingers on this pitch with nine. Not only were the half-season splits gaudy, but his home/away numbers didn't coincide either.

Truist Park (formerly SunTrust Park) ranked 15th in HR Park Factor last season, where Soroka posted a modest 1.07 HR/9. While this number is undoubtedly sustainable at his neutral home field, it made his 0.46 mark on the road appear fortunate. Since the opposing stadiums that he played in, should in theory, even out to a neutral setting as well, it's odd to see this much discrepancy. Soroka appears to have the repertoire to continue to limit the souvenirs, but it's hard to anticipate a repeat in his 2019 year-end numbers with the current trend he's riding.

Luke Weaver (SP, ARI) 190.8 ADP

Luke Weaver was enjoying a strong debut season with the Diamondbacks before a forearm injury in late-May put an abrupt end to his year. Despite a downgrade in Park Factor at his new home, his big fly numbers thrived to a 0.84 HR/9 and 9.2% HR/FB. These figures were much superior to his pre-2019 1.27 and 14.6% respective marks, so it stands to reason that his batted ball metrics would have improved to achieve these results.

This was not the case for Weaver as his Statcast metrics set new personal lows and placed below the league average in all areas except for pull rate. This measure stood as the only number not to worsen, but the slight decrease directly resulted in more hit balls to center than to the opposite field. His EV on his line drives and fly balls also scooched up from 92.4 MPH to 94.3 MPH, which would have finished in the bottom-10 if he had the innings to qualify.

Weaver likely didn't get enough of a sample size in 2019 and it's a near certainty that negative regression will find the 26-year-old in 2020. He'll have to keep batters whiffing to help negate this expected loss, but if he can keep his pull rate down with a possibly un-juiced ball, the drop may not be as significant. I'm a bit lower on Weaver than most since his batted ball data indicated he was more fortunate than other hurlers, but there is intriguing upside in his hitter-friendly division.

Cole Hamels (SP, ATL) 251.7 ADP

Cole Hamels shaved his HR/9 from 1.37 in 2018 to 1.08 with the Cubs last season, which was much closer to his 1.04 career mark. His 12.9% HR/FB also resembled a number resemblant to his lifetime level (11.8%), suggesting his problematic 2018 campaign was an outlier in HR performance. Although if we look at the illustration below, we see his underlying metrics from 2019 place him closer to his stats from the year previous.

Other than Hamels' fly-ball and pull rate improving from the year previous, he allowed harder contact than in 2018 and in his past seasons combined. He set career-worsts in Barrel% and EV, while his 40.6% Hard% also came in at a new personal high and nearly a 5% decrease from his lifetime mark (35.8%). His 21.5% FB% in 2019 may look appealing, but it was outweighed heavily by an 18.5% mark in April and May followed by a 24.0% clip the rest of the way. Among pitchers with 400 BBE, Hamels also finished in the bottom-five in Avg HR Distance (410') and FB/LD EV (94.5 MPH), meaning he was serving up moon shots.

The southpaw's 91.4 MPH velocity on his fastball was his lowest on the radar gun since 2012, and it bottomed out at 90.0 MPH over the last two months of the 2019 campaign. These dwindling figures forced me to bump him down my rankings since his move to Atlanta also comes with depreciation in Park Factor. Entering his age-36 season, it's hard to envision Hamels keeping his home run numbers down with his Statcast metrics in decline and the regression monster standing on his doorstep.

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