Breaking Down the Improved Heath Hembree

Featured image courtesy of (July 20, 2018 – Source: Duane Burleson/Getty Images North America)

The Boston Red Sox have several players enjoying career years, but one has slipped under the cracks. Longtime reliever Heath Hembree is in the midst of an incredible stretch and has been one of the Red Sox most reliable relievers. Throughout his career, Hembree has been inconsistent at best, so what has sparked this change?

Who is the Improved Heath Hembree?

The first question to ask is if this is just a hot stretch. Players are certainly capable of going of week-long stretches of dominance before returning to their norm. So, just how long has Hembree been pitching well?

The answer to that is basically since June. Starting on June 2nd, Hembree has thrown 16.2 innings to the tune of a 2.16 ERA. Opposing batters are posting a measly .150/.271/.267 slash line against him, and he’s striking out 14.0 batters per nine innings. The 16.2 inning represent 40.7% of his total innings on the season (41), so this isn’t the case of a small sample size.

Now that we’ve established this recent stretch is more than just a hot streak, let’s look at some underlying information. Let’s look at how much of this is due to a changed approach on the mound, and how is due to luck.

Analyzing Hembree’s Pitches

Throughout his six-year career, Hembree has primarily relied on his fastball. He turns to his heater 59.4% of the time, throws a slider 31.8% of the time, and uses his changeup and curveball sparingly. In 2018, Hembree has followed that same general pattern. He’s thrown 55.3% fastballs, 36.9% sliders, and 7.7% curveballs.

Ever since June, Hembree has still used essentially the same pitch selection. Over the last 16.2 innings, Hembree’s thrown 57.1% fastballs, 32.2% sliders, and 10.6% curveballs. His fastball velocity sits at 94.9 mph, right in line with his career average of 94.3. Based on pitch selection alone, it looks as though Hembree hasn’t changed anything. So, let’s now take a look at the underlying peripherals to see if luck has anything to do with it.

Analyzing Hembree’s Luck

While at first it looks as though Hembree has improved across the board, his underlying statistics tell a different story. While he has improved his strikeout rate (14.0 K/9 since June, 12.3 K/9 on the season), most of his other peripherals don’t tell an encouraging story.

Hembree’s control has actually been more sporadic than ever, as his BB/9 sits at a very bad 5.4 since June. On the season, he’s walking 4.2 batters per nine innings, the second-worst rate of his career. The fact that he hasn’t changed his pitch selection and his control has actually been worse strongly implies this run was aided by a lot of luck.

Unfortunately for Hembree, it doesn’t end there. Since the start of June, opponents have an unsustainably low .219 BABIP against Hembree. The league average is around .300, and that statistic will regress towards the norm as time goes on. Since June, his FIP, a stat similar to ERA which attempts eliminates batted ball luck, sits at 3.40. While this isn’t a bad number by any means, it’s a far cry from his 2.16 ERA over that same time span.

Digging a little deeper, his batted ball luck also tells a mixed story. If a pitcher cannot get a strikeout, then they want to induce weak contact on the ground. If Hembree has increased his soft contact allowed and decreased his fly ball rate, then he’s clearly doing something well.

As far as soft contact goes, Hembree has slightly improved over the past two month. Per Fangraphs, since June Hembree has allowed soft contact 26.5% of the time. Compare that to his soft contact rate of 20.6% on the season, and there’s been some notable improvement in this regard.

However, the ground balls are a different story. Over this hot stretch, Hembree has actually gotten significantly worse at inducing ground balls. Since June, 29.4% of all contact against Hembree has resulted in ground balls. Compare that to his season rate of 29.4% and Hembree is actually allowing more balls in the air. This is obviously not a good thing, and yet another sign that this run of success is aided by considerable luck.

Unfiltered Thoughts on Heath Hembree

Heath Hembree has been one of the better arms in the bullpen for the last two months, but don’t expect that trend to stick. Over the past few months, Hembree has been aided by an unsustainably low BABIP while increasing his walk percentage and decreasing his ground ball rate. All these signs point towards some ugly regression that will bring Hembree’s numbers back up.

However, there are signs that Hembree is improving. His increased strikeout rate is obviously a good thing, and

Dave Latham

Engineer by day, sportswriter by night. Follow me @DLPatsThoughts

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