Brandon Beachy turned in one of baseball’s most surprising performances this past season. After rising through the Atlanta Braves’ minor league system in 2010, Beachy wrestled the fifth starter slot away from Mike Minor in 2011. The undrafted Beachy shocked the baseball world, posting a 28.6% strikeout rate, 3.19 FIP and 3.16 xFIP en route to 2.8 win season. While his success was unexpected for many analysts, Beachy had a secret weapon that may have been the key to his transformation.

A look at Beachy’s Pitchf/x numbers from the past two seasons show that Beachy started using his slider again in 2011.

Brandon Beachy Pitchf/x FB% FC% SL% CU% CH% 2010 55.2% 6.8% – 11.5% 22.9% 2011 50.3 9.4% 19.1% 9.5% 10.2%

In this instance, the stats match up with the story line. Early last season, Beachy announced that he was going to reintroduce a slider to his repertoire. Beachy used the slider as an out pitch in college, but the Braves asked him to scrap it in favor of a curveball after he signed. A day after that story came out, Beachy went out and dominated the Milwaukee Brewers for six innings. That performance inspired our own Dave Cameron to write up a post that claimed Beachy was here to stay. A big reason for Beachy’s sustained success was his reliance on his slider throughout the season.

Beachy’s new toy became his second most valuable pitch last season, according to his Pitchf/x pitch values. His confidence in the pitch was even more impressive. Beachy quickly realized that he could get strikeouts with the pitch, and he was right. Beachy’s slider had the highest Swing-Miss% of any of his pitches against both righties and lefties. Lefties were able to put the ball in the air when they made contact, but righties consistently pounded the slider into the ground, leading to a 52.1% ground ball rate.

When Beachy got ahead of batters, the slider was his dominant pitch. He relied on it heavily when he had two strikes on batters. Against righties, Beachy threw his slider 33.3% of the time in 0-2 counts. That number jumped to 40% in 2-2 counts, and sat at 32.1% in 2-2 counts. Outside of his fastball, it was the pitch he threw the most in those situations last season.

Beachy still relied on his slider against lefties, but he mixed in breaking pitches against opposite-handed hitters. Beachy was more willing to throw his curve or his change-up to keep lefties off balance. Against left-handers, Beachy used his change-up when he got behind in the count. In every count in which Beachy trailed a left-hander — with the exception of 3-1 — he threw his change at least 20% of the time. When he needed strikeouts against lefties, he opted for a fairly even mixture of sliders and curves. With the addition of his slider, Beachy used a four-pitch arsenal against lefties.

And when the pressure was at its highest, Beachy relied on his slider even more. Beachy’s slider usage actually increased when men were on base or they were in scoring position. With the bases empty, Beachy threw his slider about 17% of the time. That number rose to nearly 24% with men on base and in scoring position. He threw his change-up and his curveball less frequently in these situations.

Since reintroducing his slider, Beachy has gone from a fringe-starter to a potential top-of-the-rotation stud. Even though he didn’t throw his slider for a number of years, it instantly became his most reliable breaking pitch in every situation. Some doubts might remain about whether Beachy can continue to dominate, but as long as he keeps throwing his slider, he’s a good bet to repeat. Yeah, Brandon Beachy is definitely here to stay.

*Big thanks to Joe Lefkowitz’s Pitchf/x site. Without it, this article would not have been written.