Grilli’s Fastball Keys Resurgence

Jason Grilli was just a guy Neal Huntington plucked out of the Phillies’ minor league system back in 2011, yet another nebulous asset added in the Pirates’ attempts to rebuild on the cheap. Two years later, a 34-year-old once with little but gas and a prayer could be Pittsburgh’s opening day closer. He turned 2011’s resurgence into a full breakout relief season in 2012 — although his ERA fell from 2.48 to a still sharp 2.91, Grilli’s strikeout and walk rates improved greatly; his FIP fell from 3.30 to 2.80 bolstered by an incredible 13.8 strikeouts per nine innings.

Joel Hanrahan has been shipped out to Boston. Grilli, rewarded with a two year, $6.75 million contract, is the heir to Pirates’ closer position. Can the new Jason Grilli hold up in the ninth inning?

Like many right-handed relievers, Grilli uses the classic fastball-slider combination. At 92-93 MPH on average with the fastball and able to hit the mid-90s, Grilli always possessed major league mound power. But he lost control of it in 2009. His fastball was called a ball over 40 percent of the time, his walk rate skyrocketed to 5.32 per nine innings, and he washed out with both Colorado and Texas.

A torn quadriceps and ruptured knee ligament sidelined Grilli for the entire 2010 season — he didn’t throw a single professional pitch. But in 2011 he latched on with Philadelphia’s Triple-A squad and dominated hitters — he struck out over 11 per nine innings, and more importantly, he walked just 3.3. It wasn’t enough to push onto Philadelphia’s major league roster, but Pittsburgh was able to pluck Grilli away thanks to a clause in his contract. Grilli walked 4.1 batters per nine innings with the Pirates, a low enough total given a strikeout rate over 10.0 per nine, and he posted a decent 3.30 FIP to go with the 2.48 ERA.

In 2011, Grilli’s fastball went for a ball just 31.4 percent of the time on 315 pitches. Grilli appeared a changed pitcher, and his 2012 removed any lingering doubt. He threw 31.5 percent balls with his fastball in 2012 on 682 pitches. Although BB/PA — or BB/9 — doesn’t stabilize until at least 550 batters faced, nearly 200 more than Grilli has faced as a Pirate between 2011 and 2012, per-pitch statistics tend to stabilize much quicker.

The uncertainty in any binary statistic — like walks per plate appearance or balls per pitch, where the answer on any single measure is “yes” or “no” — can be easily calculated thanks to the nature of binomials. In the case of balls per pitch, the calculation is as follows:

Here, B is the rate at which a pitcher throws balls. For Grilli, B is 0.315. Over 682 pitches, sigma is a mere 0.0177 — we would expect his ball percentage to sit within 1.7 percentage points of 31.5 around 65 percent of the time and within 3.4 percentage points around 95 percent of the time. Even the extreme high end comes nowhere near the Grilli of old, the one who walked over five batters per inning and threw over 40 percent of his fastballs for balls.

Grilli’s fastball had a 94.3 MPH average velocity in 2012, a 1.3 MPH increase, and the combination of better control and velocity had distinct positive effects. Grilli was able to rely on the fastball to get out of hitters’ counts and he even pushed the whiff rate on the pitch up to a tremendous 15 percent — only four percentage points below the slider. Such a quality fastball makes falling behind early less of a burden. Grilli allowed just a .300 wOBA on 103 counts passing through 1-0 last season, compared to a .361 career average. Only 29 of these 103 plate appearances went to 2-0, with just 20 balls coming on 78 fastballs (25.6 percent).

There will naturally be some hesitation around the idea of Jason Grilli as closer. His two saves last season was a career high and he spent nearly 15 seasons as nothing more than a journeyman. But Grilli has always possessed a big-time major league fastball — it’s what earned him the fourth overall selection in 1997 and what kept him getting minor and major league opportunities through 2011. Since coming up with the Pirates in 2011, Grilli has thrown over 1,000 fastballs with a combination of control and power far better than anything he had ever shown before.

Risk exists, as it does with any 36-year-old reliever with a major injury in his recent past — or just any reliever at all. But Grilli has shown a legitimate transformation into a strike-pumping reliever with a nasty one-two fastball-slider punch, a profile many teams put at the closer position year-in and year-out. The Pirates called it his job to lose. Grilli’s harnessed fastball has turned him into no less than an excellent reliever over the past two seasons. If he can keep hold of the reins in 2013, Grilli can thrive much the same as closer.